Yes, Russian uses "implied actions" (ellipsis) quite extensively:
- Дени́с лю́бит кра́сное вино́, а О́льга [лю́бит] бе́лое [вино́].
- Дени́с лю́бит футбо́л, а О́льга - нет [не лю́бит].
But the way you've built your sentence, it just doesn't work that way. You used a conjunction (до того́ как) to join a clause (кото́рая была́ в регио́не) and a nominal (други́е). If you use a preposition instead, it works:
- Э́то культу́ра, кото́рая была́ в регио́не до други́х.
Even better to use 'ра́ньше' (a comparative adverb):
- Э́то культу́ра, кото́рая была́ в регио́не ра́ньше други́х.
The English version works only because 'before' is both a preposition and a conjunction:
- ...before others.
- ...before others were there.
To illustrate why it's important, let's take a look at this example:
- John finished in time because Ann helped.
You can't just take away the verb (helped). It won't work. But if you change the conjunction (because) to a preposition (because of / thanks to), it works:
- John finished in time because of Ann.