Decades: 1180s 1190s 1200s 1210s 1220s - 1230s - 1240s 1250s 1260s 1270s 1280s
Years: 1225 1226 1227 1228 1229 - 1230 - 1231 1232 1233 1234 1235
Births
Deaths
... union of A and B is standardly written "A ∪ B". Formally: x is an element of A ∪ B if and only if x is an element of A or x is an element of ...