How was alexander able to turn porus’s elephants into a kind of war weapon?

Alex's soldiers and cavalry were able to box in/encircle the elephants; many of the drivers  were killed by spears; elephants grew tired and many were wounded; w/o drivers they were  disorganized and turned every which way and trampled many Indian soldiers

Explanation:

these civilizations were located around fertile rivers, where they could produce an abundance of crops

2. a land bridge connected asia and north america thousands of years ago.

4. crossing the land bridge would have been simple for the first migrants.

5. people might have crossed a land bridge while hunting animals.