225 years ago, the total areas of Ha Nam, Nam Dinh, Thai Binh and Ninh Binh were deepened into the sea. At the end of Jurat's era or the beginning of Bach Phan (White chalk) era, a seism movement created limestone areas of Ha Nam, Nam Dinh and Ninh Binh today. The majority of mountains lied along Day River right bank and a few of mountains located in the left.

70 million years old, sea disappeared and was replaced with new alluvial deltas. Ha Nam was consolidated by Red and Day River's silt. Besides mountains, the province was surrounded by various rivers: Red River in the East and Day River in the West, Nhue River in the North and Ninh River in the South and many other rivers flowing within the province. These natural conditions created cultural and historical identities of a complex area, which connected cultures from East to West, from North to South. It was these features that formed Ha Nam people's characteristics in the period of our nation's building and defending.

According to archaeological results, primitive men appeared in Ha Nam about 10,000 years ago, in the early New Stone Age and Ceramics Age under Hoa Binh culture. May be it was due to population boom in the primitive time, some people started growing wet rice in the delta. They were considered as pioneers to discover and exploit Red River Delta.