Noah had a family of eight, including three sons named Ham, Shem, and Japheth. All human beings in this world descended from these three sons of Noah. Shem, Ham, and Japheth each bore children, and these children continued to multiply.
Before the flood of Noah, the average lifespan for human beings was around 900 years. But the life expectancy fell sharply after the flood, from about 900 years to around 200 years, as we can glimpse from the fact that Abraham passed away at the age of 175. In contrast, it wasn’t until Noah was 500 years old that he began to build the ark, and it wasn’t until he turned 600 years that the rain came down for 40 days and nights to inundate the whole world. After the water receded, Noah and his family disembarked from the ark and the human race began to multiply again through his three sons. The people in those days still lived for a long time, so it was common for several generations to live in the same house. In other words, the whole clan lived next to one another.