GMAT Sentence Correction (SC) | Re: Along the major rivers that traverse the deserts of

HelloGMATNinja , Mikemcgarry, and other experts

The sentence just says that 'at least 6,000 years'. How do we know just from this phrase that it still continues?

If the sentence was:
..............and good growing conditions both encouraged farming traditions that, in places, endured for 6,000 years.

Will the use of simple past be correct here?


Thanks