The first recorded history of Sibuyan Island and Cajidiocan was in 1570, when Martin de Goiti, Spanish conquestador and Navigator under the service of Spain landed on Sibuyan Island in May 10, 1570. De Goite noted Sibuyan Island to be rich in Gold and mentioned that it was good source of fresh drinking water. Source of it was flowing through veins of various minerals as healtful. He found some Mangyanes or May-as and native painted people (pintados) living along the coast.

On November 2, 1571, The island together with Tablas and the settlements along Mahalud river in Panay island were established into a single encomienda under Don Alvaro de Angulo, belonging to Panay in the Pintados (Iloilo) province. The islands of Romblon, including Tablas, Sibuyan, Banton, Simara, Sibale and Hambil belongs to this province which later was renamed Alcaldia de Arevalo. From 1636 until 1703, building of churches were started in Romblon pueblo, Banton (Timaya and Mainit), Cibuyan (Cauit and Cahidyocan) and Tablas (Cabolutan, Odiongan and La Lauan). It's only a pity that the old facade of Santa Barbara parish church in Cajidiocan was not spared from careless renovation. The church was renovated in 1957 and completed in 1961 destroying much of the original barroque architecture of the building while its original retablo was replaced by a modern one of no artistic design nor segnificance.

In 1716, Capiz was created a separate province out of the old Alcaldia de Ogtong or Arevalo (Iloilo), formerly called Panay in the Pintados province. The new province included the islands of Romblon group and the valley of Aclan in northwestern Panay island. In 1734 Philippine map published by the Spanish government, affirmed pueblo de Sibuyan already existed located at the present day Cajidiocan as early as 1636 together with visita de Cauit (Azagra). Cajidiocan was the first settlement in Sibuyan Island to be organized into a pueblo. Thus, pueblo de Sibuyan was always referred to as pueblo de Cajidiocan. In 1779 pueblo Sibuyan church records on Bautismos included visita Cauit belonging to its parish, mision de Cambulayan (founded in 1779), mision de Cabatangan (1790), visita de Pag-alad (1813), Mision de Naylog (1820), mision de Cambalo (1842), mision de Canjalon (1842), mision de Cangumba (1842), mision de Mabolo (1847), mision de Cambajao (1848), mision de Ipil (1848), mision de Danao (1848), rancheria de Espana (1855) and rancheria de Infiel (1861). All these settlements, missionary centers and visitas in the island of Sibuyan belongs to the province of Capiz.

In 1850, people started using family names beginning with letter "R" as decreed by Spanish Governor-General Narciso Claveria issued in November 21, 1848. Pueblo Sibuyan was renamed Cajidiocan derived from the name of certain sugar palm tree known in vernacular as 'Idiok', hence the name 'Cajidiocan' meant a place with plenty of 'Idiok' trees. On July 23, 1848, however the name pueblo de Sibuyan remained its official name until March 19, 1853, when the PMC de Romblon was established.

On March 19, 1853, the islands of Romblon was organized into a Politico Militar Commandancia del Distrito de Romblon under Commandante de Infanteria Don Ramon Vieytes as its first Commander (petty Governor) taken from Capiz province with four existing towns namely, Romblon which was designated as the new capital town, Banton which included Sibale, Cajidiocan originally known as pueblo de Sibuyan and Looc. The full text of the superior decree in Spanish: 'El superior decreeto No. 206 del 19 de Marzo de Ano de 1853 mandato creacion Commandante Politico Militar del Distrito de Romblon de la provincia de Capiz". On February 18, 1854 the royal order was confirmed by a superior decree. Full text in Spanish: "La real orden No. 57 del 18 de Febrero del ano de 1854 approvado la creacion de el Distrito Politico Militar de Romblon con denominacion de Commandante Militar de Romblon".

The following year of 1855 recorded a tremendous leap on the creation of new pueblos or parishes under the new government. 17 new pueblos were added to the existing four. However, visita de Sibale remained part of pueblo de Banton. The new pueblos that were created in 1855 were: Guintiguian (San Agustin), Simara (Corcuera), Odiongan, Andagao (Calatrava), Parpagoja (San Andres), Tingaray (Ferrol), Catolog (Santa Fe), Cabalian (sitio of Agmanic, Santa Fe, formerly a pueblo), Saban (sitio Sabang, Danao Norte, Santa Fe, formerly a pueblo), Lauan (Alcantara), Guinbirayan (barangay of Santa Fe), Cauit (now named barangay Azagra, San Fernando), Pag-alad (San Fernando), Isabel (barangay Cambalo, Cajidiocan), Princesa (sitio Cangumba, Azagra, San Fernando), Espana and Magallanes (Magdiwang) were all created into separate municipalities or pueblos including rancheria de Infiel (Dulangan, Magdiwang in 1861). By 1861, Sibuyan had 8 numbers of pueblos or parishes, namely: Magallanes, Isabel, Cajidiocan, Princesa, Cauit, Pag-alad, Espańa and Rancheria de Infiel (Dulangan), but in January 11, 1868, only three pueblos were retained in Sibuyan Island, namely: Cajidiocan, Azagra and Magallanes.

The Politico Militar Commandancia del Distrito de Romblon was converted into Politico Militar Commandancia dela Provincia de Romblon on January 11, 1868. This happened during the incumbency of Commandante de Infanteria Don Joaquin Corillo who was installed as Commandante of the province since 1866. As a consequence, Don Corillo being the first official Governor of the new province reorganized the local municipal government. Thus 15 existing pueblos (municipios) or parishes were abolished namely: Guinpuc-an (barangay Carmen in San Agustin), Cagbagacay (Santa Maria), Pag-alad, Rancheria de Infiel refers to Ranch of Savaged or Wild People found at barangay Dulangan, Magdiwang. This refers to the Mangyanes or May-as tribal people previously organized into an autonomous pueblo in 1861. The mission of Rancheria de Infiel was to establish a separate pueblo for them in-order to tame and convert these wild people and their children who fled to the mountains who were against conversion but all efforts failed, hence it was also abolished, including the former pueblo of Espańa, and Isabel which reverted to its former name Cambalo and was annexed back to Cajidiocan as a barrio and Princesa. (Please note that barrio Otod got its name from the Hiligaynon word 'Otod' meaning brother or sister since it was named after the princess of Spain, sister of Queen Isabela). When Princesa was abolished as a pueblo, it reverted to its old name Cangumba. For this reason, a new barrio was created taken from territories of visita de Cangumba which was named barrio Otod in 1894 as a memorial to the Queen's sister. Today, Cangumba is only a sitio of barangay Azagra in San Fernando municipality. The other pueblos abolished were Odiongan, Andagao, Parpagoja, Tingaray, Catolog, Sabang, Lauan and Guinbirayan. While the 7 pueblos retained were the following: Romblon, Badajoz (now San Agustin formerly Guintiguian renamed Badajoz on August 28, 1868) Banton, Corcuera, Looc, Cajidiocan, Azagra (San Fernando), and one missionary center, the mision de Magallanes (Magdiwang) and one semi-autonomous visita, administered from pueblo de Banton, visita de Concepcion. Before the end of Spanish rule, three of these pueblos were restored, namely: Odiongan, Santa Fe and Despujols (San Andres).

Civil government was established under the Americans on March 16, 1901. A total of 11 new municipalities were created in the province namely: Badajoz, Banton, Cajidiocan, Corcuera, Looc, Magallanes, Odiongan, Romblon the Capitol, Despujols, San Fernando and Santa Fe. The province of Romblon was abolished in July 15, 1907 and incorporated back to the province of Capiz as a sub-province due to insufficient income. Concepcion or Sibale however was separated from the rest of the province and incorporated into the province of Mindoro. For this reason, it was converted into a separate local government unit known as the Municipal District of Concepcion as attested by a Romblon map showing the provincial maritime boundary of Mindoro (now it is part of Oriental Mindoro) encroaching the island of Maestro de Campo published in 1914 and issued by the U.S. Army Map Service, Corps of Engineers. Please check Philippine Map Series S501 reprinted in 1954 for reference. On March 10, 1917, Romblon was restored as a regular province and the former municipal district of Concepcion belonging to Mindoro was recalled back to the province.

In June 8, 1940, the special municipality of Sibuyan was established through the passage of Commonwealth Act No. 581 sponsored by a Bantoanon legislature, Congressman Leonardo Festin. Cajidiocan was made the seat of the Speical Municipality of Sibuyan incorporating the abolished municipalities of Magdiwang and San Fernando. The former towns of Magdiwang and San Fernando were represented only by a special councilor at its municipal council based in Cajidiocan town. On May 26, 1946, the special municipality of Sibuyan was abolished through the passage of Republic Act No. 38 sponsored by newly elected congressman, Hon. Modesto Formelleza and took effect on January 1, 1947. Cajidiocan and the other two municipalities in the island of Sibuyan were restored back to its former status as independent municipalities.

Development of Cajidiocan's Barrios / Barangays:

Cajidiocan was one of the earliest established pueblo or parish in the province of Romblon. The first census showing breakdown of its barrios was in 1894 conducted by Spanish authorities reporting a total of 9 existing barrios in pueblo de Cajidiocan, namely: Casco de Poblacion, Cambijang, Cambajao, Sugod, Suong, Lumbang, Marigondon, Cambalo and Danao with a combine population of 3,257 (1894). In 1897 additional of 2 barrios were added. These were Taguilos and Cambicang (both taken from Marigondon). However, barrio Suong was abolished and absorbed by barrio Poblacion on same year making a total of 10 barrios in 1897. Its total population in 1897 was 3,283.

At the end of Spanish regime, the territory of Cajidiocan extended only from barrio Danao in the north to barrio Cambijang in the south. The territory west of Danao in what is now barangay Cantagda was formerly part of pueblo de Magallanes (Magdiwang) then known as barrio Cabangajan. Barrio Cabangajan was abolished in 1901 and instead of joining Magallanes opted to be annexed to barrio Danao as sitio in Cajidiocan municipality. Romblon provincial government was established by the Americans in March 16, 1901. A total of 3 new barrios were created in 1901, namely: barrio Alibagon (taken from Cambajao), Gutivan (taken from Sugod) and Lico (taken from Marigondon). However, barrio Cambicang was abolished on same year and was annexed back to barrio Marigondon, its mother barrio. In census conducted by the Americans in 1903, there were a total of 12 barrios, namely: Poblacion, Alibagon, Cambajao, Cambalo, Cambijang, Danao, Gutiban, Lico, Lumbang, Marigondon, Sogod and Taguilos. In 1901 census, Cajidiocan registered a total population of 4,464.

In March 10, 1917 the province of Romblon was restored as a regular province since it was abolished in July 2, 1907 to become a sub-province of Capiz. On that same year of 1917, due to reorganization and the province's difficult financial status as a newly restored province, the former municipality of Magallanes was abolised and annexed to Cajidiocan. In 1918 official census, Cajidiocan had a total of 18 barrios. Twelve of which were located in Cajidiocan and 6 were from the former municipality of Magallanes, namely: Magallanes, Silum, Jao-asan, Ipil, Dulangan and Agsao. Magallanes restored as independent municipality on March 1, 1933 with a new name, Magdiwang as a tribute to the Magdiwang faction of Andres Bonifacio, Supremo of the Katipunan.

In 1968, through Republic Act No. 3384, Cantagda was created into a separate barrio taken from barrio Danao while Lumbang was split into two barrios of Lumbang Este and Lumbang Oeste on that same year. Cajidiocan is site of Sibuyan District Hospital established through the efforts of then congressman Jose D. Moreno through the passage of R.A. No. 2400 in 1958. Presently, Cajidiocan has a total of 12 barrios or barangays to-date namely:

1. Alibagon
2. Cambajao
3. Cambalo
4. Cambijang
5. Cantagda
6. Danao
7. Gutivan
8. Lico
9. Lumbang Este
10. Lumbang Weste
11. Marigondon
12. Poblacion
13. Sugod
14. Taguilos