The kingdom of Banjarmasin on the Barito River in southern Kalimantan was reputedly founded by Empu Jamatka in 1387. The capital lies on the island Tatas. The kingdom became an important source of diamonds, bezoar stones, and dragon’s blood (a plant extract) but was dependent on Java for the supply of rice and was tributary to the Javanese states of Majapahit, Demak, and Mataram, respectively. Its ruler converted to Islam around 1520, and the sultanate received many refugees from the north coast of Java after the fall of Surabaya to Mataram in 1625.
In the 17th century pepper, gambier (used for chewing betel), gold, and rattan became major trading commodities, attracting Chinese traders as well as the Dutch and English East India Companies. Both the Dutch and the British attempted to enforce monopolies in the port, but the various agreements with sultans were unenforceable as economic and political power was concentrated in the hands of powerful pepper planters. The Dutch were forced to leave in 1669. The British closed their trading post in 1707.
On request of the sultan the VOC sent ships to Banjarmassin again from 1726 onwards. Both parties signed a treaty in 1733, in which the Company got the monopoly on the pepper trade and the obligation to protect the sultan against his enemies. The monopoly was often eluded by smugglers. In 1747 Governor General Gustav Willem van Imhoff ordered a blockade of the harbor for all non-Dutch ships. Two years later the VOC opened a trade post on Tatas. In 1756 the sultan asked the support of the VOC against the Bugis. In the treaty between Sultan Banjermassin and Johan Andreas Paravinci of October 1756, the VOC got permission to build a stone fort to protect her own and the sultans interest: Fort Tatas.