Robertus Junius was a Dutch Reformed minister who came to Taiwan in 1629 and followed Candidius as missionary to Sinkan. He learned the Siraya language and preached and wrote catechisms in it.

By 1633 Sinkan had largely converted. In 1636 he opened the first school there, teaching seventy boys to read and write their own language in Roman letters — the script later called the Sinkan writing, which the Siraya were still using for contracts more than a century after the Dutch left.

His work was not confined to the pulpit. When the Company sent troops against villages that resisted, he went with them; on his watch, at the end of 1641, more than a hundred inib priestesses from Mattau, Soulang and other villages were banished from their homes. In these years mission and rule were two sides of one thing, and he was present on both.

He left Taiwan in 1643. By then more than 5,400 people in six villages had been baptised, and five to six hundred attended every Sunday. He went on as a minister in the Netherlands and died in 1655.