Except for the far west which was part of the island of Tenochtitlan, the Peñón de los Baños and a couple of very small islands in-between, the territory of the borough was covered by Lake Texcoco from the pre Hispanic period into the colonial period. The oldest human settlements in the area were located in the Mixuhca and Peñón de los Baños, which were both originally islands in Lake Texcoco. The eastern end of Tenochtitlan was associated with docks and markets that handled the produce and other items that came over the Lake's waters into the city from other parts of the Valley of Mexico such as Texcoco, Chalco and Xochimilco. The lake in this area also contained part of the Nezahualcoyotl Dike, built to separate the shallow waters.