Complex sentence: Postage stamps and postal history of Portuguese India goes back to the earlier days of the colony though the postal history of that time is obscure, but regular mail is known to have been exchanged with Lisbon from 1825 on.
Split into simpler sentences: Postage stamps and postal history of Portuguese India goes back to the earlier days of the colony, though the postal history of that time is obscure. Regular mail is known to have been exchanged with Lisbon from 1825 on.