Finally, the growing population was probably fed by increasing the number and size of irrigated fields. Teotihuacán may have achieved some religious significance and its shrine (or shrines) may have served as an additional population magnet. It is also probable that as early as 200 B.C. In addition, Teotihuacán's elite may have consciously attempted to attract new inhabitants.
Such success may have attracted immigrants to Teotihuacán.
With Cuicuilco eliminated as a potential rival, any one of a number of relatively modest towns might have emerged as a leading economic and political power in Central Mexico. Around this time, the largest of these centers, Cuicuilco, was seriously affected by a volcanic eruption, with much of its agricultural land covered by lava. Prior to 200 B.C., a number of relatively small centers coexisted in and near the Valley of Mexico.