system
Given the following post, respond as if you're commenting on Reddit:
human
[Doctor Who] How come the doctor never runs into other time lords throughout history? I know he is the last one, but they’re time travelers.. shouldn’t they still be around in some capacity?
gpt
There's two major factors as to why he doesn't:

1) Most Timelords barely left Gallifrey outside of the Time War era. The Doctor is *extremely* unusual in the amount of time he actually spends in other eras. Even The Master doesn't come close.

2) He can't normally go back over his own timeline - and his timeline includes major incidents on Gallifrey, which has a special time lock that prevents anyone travelling backwards with respect to *its* timeline. As such he generally can't encounter any Timelords from *before* those incidents - although Timelords that are never going to make it back to Gallifrey are fair game.

Neither of those are 100% protections, but combined they make it such that he's about as likely to run into another timelord as he is to run into a different incarnation of himself.