Israel does eventually subdue and take the Promised Land of Canaan. Over many years the new nation of Israel moves through various governmental systems, a period of judges followed by monarchy. The monarchical period began with a United Kingdom, but through sin, devolved into a Divided Kingdom; the Northern half was called Israel with Samaria as its capital and Southern half was called Judah with Jerusalem as its capital. The Northern Kingdom was ruled by a continual succession of wicked kings and God allowed them to be conquered by pagan Assyria in 722 BC. The Southern Kingdom had several godly kings and God allowed them outlast the North by another 136 years. In that period, Babylon conquered Assyria and then Judah, the Southern Kingdom, in 586 BC.
“4 “thus says the LORD of hosts, the god of Israel, to all the exiles whom I have sent into exile from Jerusalem to Babylon, 5 ‘build houses and live [in them;] and plant gardens and eat their produce. 6 ‘take wives and become the fathers of sons and daughters, and take wives for your sons and give your daughters to husbands, that they may bear sons and daughters; and multiply there and do not decrease.” (Jer 29:4-6 NAS95)
As Southern Kingdom of Judah was in the midst of falling and being taken away into captivity to live in Babylon, God instructed His people to build homes, plant gardens, marry, and have children; In the midst of such trying circumstances, God specifically commands them to be fruitful and multiply.