Paul Gepts, who should know, says that the bit of Mexico featured yesterday is pretty important:
This particular area of the state of Jalisco is part of the proposed Mesoamerican center of domestication of common bean (Kwak et al. 2009 Crop Sci.).
Here’s the relevant quote from that paper:
In the Mesoamerican gene pool, a single cluster groups most of the domesticated type, which confirms previous observations suggesting a single domestication located in the state of Jalisco form this gene pool (Gepts et al. 1986; Papa and Gepts 2003; Kwak et al. 2009).