The goes back to the prehistorical era. The oldest dated evidence of human settlement on the high plateau in the Eastern Ranges of the Colombian Andes has been found in El Abra, within the municipality of Zipaquirá, Cundinamarca. At this rock shelter on the northern edge of the Bogotá savanna, stone tools and chopper cores have been carbon dated at 12,500 years BP. Other early sites of inhabitation of the area have been discovered at Tibitó (11,400 BP), Tequendama (11,000 BP) and Checua (8500 BP), with later settlements in Mosquera (3135 BP), Chía (3120 BP), Junín, Zipacón and Tausa. Younger ceramic artefacts were found around Lake Herrera, the namesake of the Herrera Period that is defined as from 800 BC to 800 AD. The period from 800 to 1537 AD, when the Spanish conquered this area, is characterised by one of the four grand civilisations of the Americas; the Muisca period.