Complex sentence: He was probably tried in a magistrates' court on charges of political sedition or membership of a banned organisation, but the records do not survive, because all such documentation was routinely destroyed after six years by the British colonial administration.
Split into simpler sentences: He was probably tried in a magistrates' court on charges of sedition or being a member of a banned organization. Records do not survive; all such documentation was routinely destroyed after six years by the British colonial administration.