There were no Europeans in the region between 1644 and 1649, but in 1649, before negotiations with the different Indian tribes, Matias Beck arrived in Ceará to explore silver mines of Maranguape. Good-quality silver was not found however. In this period the Dutch built another fort, by the banks of river Pajeú, and named it Fort Schoonenborch after one of their commanders. In 1654, the Dutch were expelled from Brazil; the Portuguese took Schoonenborch, changed its name to Fortaleza de Nossa Senhora de Assunção (The Fortress of Our Lady of the Assumption), and the different Indian tribes that had made alliance with the Dutch had to flee from Portuguese persecution.