What this means isn't exactly clear but when a pattern like this emerges that is repeated so frequently and with such precision it almost always means something significant.
The Teotihuacan is one of the great mysteries in history. It is believed to have started about 100 years BC and continued into the 7th century when all 200,000 inhabitants suddenly left this grand city. The city peak in influence around the 4th or 5th century and this is reflected in the other great cultures of the time such as the Mayans.
The Teotihuacan city is fun place to visit and it attracts thousands of visitors each year, especially with its proximity to Mexico City. There are giant pyramid type structures with complex apartments built for the people of that time. There's also the Avenue of the Dead to explore and beautiful well-preserved murals to seek out.