Substantial research has been carried out to decipher the Guatemala region sources. As mentioned earlier, the Guatemalan region includes the El Chayal, Ixtepeque, and San Martin Jilotepeque sources, located in southern/southeastern Guatemala. Obsidian originating from Guatemala was widely used in Mesoamerica and is found as far north as the Yucatán Peninsula, moving via a well-developed long-distance trade network that inter-connected much of the Maya area. Newer and tentative additions to the Guatemalan source area are Jalapa and Sansare. However, the El Chayal area is often seen as subsuming these two into one large source area. The Pre Classic Monte Alto culture and the Olmecs also used the Tajumulco Volcano source, in the southwest of Guatemala, a source that was almost forgotten during the Classic and Post Classic periods.