By around 900 C.E., the Classical Mayan cities were in decline. Tulum peaked around 1200-1400 C.E. in the post-classic period, as an example of the smaller city-states that still remained at this point in Mayan history. It was a major trading hub, situated as a cliff top seaport, overlooking the turquoise waters of the Caribbean. A small cove and sandy beach sits at the base of the ruins, which would have been an apt landing spot for canoes bringing goods to trade. Artifacts discovered here originate from throughout the Mexican Highlands, Cozumel, Guatemala, and Honduras.
Tulum's simpler architecture lacks the imposing pyramids and complex mosaic façades found at many other earlier Mayan sites. The stonework of Tulum and other smaller sites built during this period was much less elaborate and rougher in quality, possible evidence of a decline in political and social resources. It borrows some Maya-Toltec architecture, such as it's round, supporting vertical columns, which may indicate some cultural exchange with Chichen Itza
to the northwest. But what makes its architecture unique is the high wall that surrounds the city. It was constructed later in Tulum's history as a protective measure against the skirmishes of roaming tribes from the north which were prevalent during that period. It is from this that Tulum gets its modern name, literally meaning "Walled" in Mayan.
Tulum was one of the few Mayan sites to remain populated up until the time the Spanish arrived in Mexico, and it was one of the first glimpses of the Maya that these European explorers encountered. Juan de Grijalva spotted it from his ship during his reconnaissance trip around the Yucatan in 1518, but could not land here due to reefs guarding its shores. His observations laid the groundwork for the subsequent conquistador invasion