people died in ~ because of sins,
Nuh 71:25-26
Surah Nuh tells us that Noah was sent to warn his people,
to ask them to serve Allah
and keep their duties to Him and obey Noah, that Allah may forgive
of their sins (what kind, the Qur'an didn't say). Noah's call
resulted in greater repugnance and pride, persisting in their own
gods, and because of their sins they were drowned. Noah called
upon Allah not to leave any disbeliever in the land
(Nuh 71:26).