In 2004 Beta Analytics of Miami, Florida (USA) dated the Starchild Skull using C14 (radiocarbon) dating, and found it to be 900 years old (+/- 40 years).
The adult human female skull found with the Starchild was independently radiocarbon dated to 900 years old (+/- 40 years), indicating that both died at approximately the same time. This corroborates the story that they were discovered as part of the same burial.
For some perspective, in 1,100AD, approximately when this being died, King Henry I was on the throne in England, the First Crusade had begun, and much of Mexico was dominated by the Aztecs. The Aztecs built enormous step pyramids, created ritual sites with perfect accoustics, had a writen language and sophisticated record keeping system, mandatory public schooling for children, and had an implausibly detailed knowledge of cosmic events that has led many to speculate an alien connection. However, they were not part of daily life in the Copper Canyon region where the Starchild Skull was found. Instead the semi-nomadic tribes of the Tarahumara people who inhabited the region raised crops and kept livestock in addition to hunting and gathering.