Every other discipline on this atlas carries a founded-year fact marking a defensible single moment, an at-least-somewhat-arbitrary but well-documented turning point such as a landmark publication or an institutional founding. Mathematics has no comparable single moment: formal deductive mathematics reaches back at least to Euclid's Elements around 300 BCE, with earlier practical and computational mathematics in Babylon, Egypt and elsewhere older still, and the atlas's founded-year field is a plain year integer with no era label, so it cannot honestly distinguish a BCE date from a CE one.
What would resolve this Resolved: mathematics is now recorded as founded around 300 BCE (circa), citing Euclid's Elements, the same landmark-publication convention already used for physics and chemistry on this atlas.
ResolvedHistory of mathematics, historiography of science, atlas schema designWikipedia: Mathematics