The Olmec language and Teotihuacan language are still outside this preliminary classification: the ones represented by the Olmec area and those of Teotihuacan, which are currently being studied and discovered. Though it is still difficult to prove, there is some probability that the Olmec language preceded Totonac. In contrast, it is more specific than the writings and speech of Teotihuacan, which led to Nahua's development. The Mexican population that migrated to Nicaragua later spread this language in its various variants throughout the central Valley of Mexico, even reaching the south of Mesoamerica, to Nicaragua. During the destruction and abandonment of Teotihuacan around 600, the written system of their successors, the Toltecs, was lost but may have been revived later in Aztec ideographic writing.