After Lot was saved from the destruction of the Jordan City-States he and his daughters went to live in a cave in the mountains
Genesis 19:30
“Lot and his two daughters…settled in the mountains,... He and his two daughters lived in a cave.”
However, his daughters were concerned: Their future husbands had died in the destruction of Sodom and now they were not going to get married and not have children to continue Lot’s lineage like the rest of the world was doing at this time:
Genesis 19:31
“One day the older daughter said to the younger, ‘Our father is old, and there is no man around here to give us children—as is the custom all over the earth…’”
So, the older daughter gets a very disturbing and sick idea of how to get children:
Genesis 19:32
“Let’s get our father to drink wine and then sleep with him[Have sex] and preserve our family line through our father.”
So, her plan was for her and her sister to get their father soo drunk that he would have sex with them without realizing it and would impregnate them so they could have children. That’s a pretty sick plan! Because that is incest with your parent! But they both agreed to do it in what they saw was a very desperate situation:
Genesis 19:33-35
“That night they got their father to drink wine, and the older daughter went in and slept with him. He was not aware of it when she lay down or when she got up. The next day the older daughter said to the younger, ‘Last night I slept with my father. Let’s get him to drink wine again tonight, and you go in and sleep with him so we can preserve our family line through our father.’ So, they got their father to drink wine that night also, and the younger daughter went in and slept with him. Again, he was not aware of it when she lay down or when she got up.”
And through this they both successfully got pregnant, and they both had a son:
Genesis 19:36-38
“So, both of Lot’s daughters became pregnant by their father. The older daughter had a son, and she named him Moab [Hebrew for “from father”]… The younger daughter also had a son, and she named him Ben-Ammi [Hebrew for “son of my father’s people”]…”
So, despite this weird situation for the rest of their lives Lot and his daughters and sons/grandsons seemed to have lived in or near the mountains and the plain of Jordan that was now almost completely destroyed. Eventually Lot and his daughters died, and Moab and Ben-Ammi also have children of their own. Their descendants took over the entire Jordan area and became two nations descended from Lot:
Moab’s descendants became known as Moabites and formed the nation Moab:
Genesis 19:37
“Moab; he is the father of the Moabites...”
And Ben-Ammi’s descendants became known as Ammonites and formed the nation Ammon:
Genesis 19:38
“Ben-Ammi; he is the father of the Ammonites…”
These two Lotite (Descendants of Lot) nations came to dominate the Jordan valley that was mostly destroyed.