It is not known how many people lived in Venezuela before the Spanish conquest; it has been estimated at around one million.[36] In addition to indigenous peoples known today, the population included historic groups such as the Kalina (Caribs), Auaké, Caquetio, Mariche, and Timoto-cuicas. After the conquest, the population dropped markedly, mainly through the spread of new infectious diseases from Europe.[36] Two main north-south axes of pre-Columbian population were present, who cultivated maize in the west and manioc in the east.[36] Large parts of the llanos were cultivated through a combination of slash and burn and permanent settled agriculture.[36]