Uxmal was dominant from 875 to 900 CE. The site appears to have been the capital of a regional state in the Puuc region from 850-950 CE. The Maya dynasty expanded their dominion over their neighbors. This prominence didn't last long. Population dispersed around 1000 CE.

After the Spanish conquest of Yucatán

Spanish conquest of Yucatán

The Spanish conquest of Yucatán was the campaign undertaken by the Spanish conquistadores against the Late Postclassic Maya states and polities, particularly in the northern and central Yucatán Peninsula but also involving the Maya polities of the Guatemalan highlands region...

 (in which the Xiu allied themselves with the Spanish), early colonial documents suggest that Uxmal was still an inhabited place of some importance into the 1550s, but no Spanish town was built here and Uxmal was soon after largely abandoned.
Even before the restoration work Uxmal was in better condition than many other Maya sites thanks to being unusually well built.