Which pre-Columbian people established one of the first sky maps and developed a complex calendar?

The Mayas

The Mayas were accomplished astronomers and developed one of the most accurate calendar systems of antiquity. Their deep interest in astronomy is evident in the astronomical alignment of their pyramids and temples, as well as in their complex calendar that combined several different cycles, including the Tzolk'in (a ritual calendar of 260 days) and the Haab' (a solar calendar of 365 days). Their ability to accurately predict celestial phenomena such as eclipses attests to their advanced knowledge of the night sky.