Why did prehistoric people spread throughout the americas?

When the prehistoric people trekked into south America toward the end of the ice age, they found a wondrous, lush continent inhabited by all manner of strange creatures like giant ground sloths and car size armadillos.

These hunter gatherers proceeded to behave like invasion species, with their population surging the crashing as they relentlessly depleted natural resources.

Then after that alot more people mustered that area, with crops and animals