Irrlicht Engine

eg. The tide of migration that set in toward the shores of North America during the early years of the seventeenth century

I asked some people in some chat rooms,they are from UK or US,they have no ideas..But,however,that sentence is just the 1st sentence of an american middle school history book

"that set in" - became established
"toward" - toward.

The tide of migration to North America that became established (became common) in the early 1600s.

(I'm not US.)