Why is there a little bit of East Timor surrounded by West Timor?

The small triangle of land on the north coast of Indonesian West Timor is the enclave of Oecussi. When Portuguese and Dutch traders first visited the island of Timor in the early 16th century, they had separate spheres of influence. The situation became more complicated with the rise of the Topasses, a class of mixed blood Portuguese-Timorese who seized control of much of the island, often at the expense of the Portuguese. In 1701, a governor newly arrived from Lisbon was forced by the Topasses to relocate his capital to the port of Lifau, which later became known as Oecussi. When the two European powers formally partitioned the island between them in the 19th century, it remained part of the Portuguese colony.