François Caron
It is not known when Van Tzum began working for the VOC. Van Tzum was sent to Siam in 1629. In 1636 he went on a boatride on Chao Phraya River with his colleagues. When Jeremias van Vliet left the factory in 1641, Van Tzum was nominated to succeed him, but first in 1643 he was appointed chief factor. He collaborated with Anthonie van Diemen in Batavia, Johan van Twist in Dutch Malacca, Maximiliaan le Maire and François Caron in Formosa, Jan van Elseracq on Deshima and the factors in Persia and at the Coromandel Coast. Van Tzum pretended to be sick when invited by the king.