why not simply follow the advice given on date sorting at help sorting here is an example taken from the first few entries in the table as of today that contains bc years and ad years that seems to be numerically sortable in the chronological not lexical manner one would hope for year city state or province countrynotes bc ticul yucat n mexico bc cholula puebla mexico bc teotihuacan m xico mexico in the valley of mexico mitla oaxaca mexico cahokia illinois united states acoma pueblo and taos pueblo new mexico united statesoldest continuously occupied communities in the united states the acoma pueblo today is known as sky city l'anse aux meadows newfoundland labrador canadathe norse explorer leif ericson established a settlement at n on this site in this is considered to the first european contact with north america