Where does “Than” come from?

Than comes from Burmese သန်း, whose original meaning is unknown.

Ancestry of “Than”, step by step

Step	Language	Word	Meaning
1	Middle English	than	then
2	Old English	þanne	Alternative form of þonne
3	Old English	þonne	then, at that time; then, soon afterward; then,...
4	Proto-West Germanic	þannā	—
5	Proto-Germanic	þan	then, at that time
6	Proto-Germanic	þam	—
7	Proto-Indo-European	tóm	—
8	Proto-Indo-European	só	this; that

Than — Etymology, Origin & Word History | Etymology Explorer