Francis Castro and Father Jose Altimura were the first Europeans to explore the Napa Valley, in 1823. When the first white settlers arrived in the early 1830s, there were six tribes in the valley speaking different dialects and they were often at war with each other. The Mayacomos tribe lived in the area where Calistoga was founded. The Callajomans were in the area near where the town of St. Helena now stands. Further south, the Kymus dwelt in the middle part of the valley. The Napa and Ulcus tribes occupied part of the area where the City of Napa now exists while the Soscol tribe occupied the portion that now makes up the southern end of the valley. Many of the native peoples died during a smallpox epidemic in 1838. Settlers also killed several over claims of cattle theft.