How did Tikal become a great Maya kingdom in a rainforest with no river?

Tikal became powerful by solving a problem: it had no river or lake, so its rulers learned to store the rain, and then used war, and probably trade, to build one of the most powerful kingdoms of the ancient Maya. It was the capital of that state, and its inscriptions call it Yax Mutal or Yax Mutul, meaning "First Mutal". "Tikal" is just a name adopted after its discovery in the 1840s.

The water problem was serious. Tikal had no water other than rainwater stored in ten reservoirs, and the rains were often unpredictable, with long droughts that severely threatened the inhabitants. A significant part of royal power rested on what rulers could provide, such as water during the annual drought through massive artificial reservoirs. The city may also have dominated a natural east–west trade route across the Yucatán Peninsula. It covered more than 16 square kilometres with about 3,000 structures, and estimates of its population vary from 10,000 to as many as 90,000.

Its history reads like a power struggle between two giants. Tikal's great rival was Calakmul, another powerful city in the Petén Basin. In 378 AD, the Tikal king Chak Tok Ichʼaak was killed on the same day that Siyaj Kʼakʼ arrived from the west, and the recorded events strongly suggest that Siyaj Kʼakʼ led a Teotihuacan invasion. Yet the foreign rulers' descendants were rapidly Mayanized. In AD 562 Tikal was beaten by Calakmul and Caracol, but in 695 Jasaw Chan Kʼawiil I captured an enemy noble and threw Calakmul into long decline.

By the end of the 9th century the city had been deserted. Its palaces were taken over by squatters, though knowledge of the ruins was never completely lost in the region.