How did Indigenous tribes get here?

Answer 1

The most accepted answer is the Land Bridge or present day Bering Strait. There is also evidence that has be uncovered that Vikings did land in Noeth America before Columbus did. Although this does it explain how the indigenous tribes in Australia settled there, which would suggest they could have been sea faring or possibly the islands we see today where mountains of another land bridge. In short there is no definitive answer as to how they traveled and settled there.

Answer 2

Nobody really knows, but the best explanation historians and scientists have come up with is known as the Land Bridge Theory. This theory states that during the ice age a path was revealed, one that stretched from Asia to Alaska. This path would eventually become flooded by the melting ice that signaled the end of the ice age, but it is assumed that tribes indigenous to the Americas used this land bridge to walk and make their home in the modern-day Americas.