It was from the Paleolithic Age that people started to live at the drainage basin of the Nakdong River. The Paleolithic men lived by traveling for hunting and collecting food using chipped stone implements and tools made of wood or bone. The remains of the Paleolithic Age that were discovered in this area fall into the period of the later Paleolithic Age (35,000 B.C. ~ 10,000 B.C.); the major relics from this period are chipped stone implements, micro-blade core, and stemmed projectile points.

In the Neolithic Age (10,000 B.C. ~ 1,000 B.C.), the earthenware and polished stone tools appeared and people started to settle for their living. The Neolithic men hunted, collected food, and fished and in some areas, people farmed or cultivated crops. In these areas, various relics from the Neolithic Age were found including living relics such as the large-scale shell mound, housing sites, and graves.

In the Bronze Age (1,000 B.C. ~ 300 B.C.), people used polished stone tools and plain coarse pottery. They initiated rice farming in full scale and formed a village on a shallow hill or field. The major graves in this period were made of dolmen and stone cist.

From the time when the new iron culture was introduced after the Bronze Age to the period when Gaya, Shilla, and Baekjae were established, there were also Byeonhan, Jinhan, and Mahan in the South. Byeonhan and Jinhan were in the Eastern area of the Sobak Mountains, which is presently the Youngnam region. Having Nakdong River as the boundary, Byeonhan was located in the West.

As Gojoseon was destructed by the Han in 108 B.C., the migrants with advanced technologies entered the Youngnam region where Byeonhan and Jinhan were located, to bring about a remarkable revolution. The ironware was spread and used instead of bronze ware. Moreover, the tile-quality pottery made through the new technology (such as a round jar with thin container wall and wide bottom) was introduced and used instead of the plain coarse pottery that was rustic and had thick container wall. Also, the graves were changed from dolmen to stone cist and outer coffin tomb. Furthermore, active local trade was formed based on iron and through such trade, the main forces appeared.

Gaya indicated the numerous power blocs that existed in the old Byeonhan region centering at the western area of Nakdong River in the period of the Three States (Goguryeo, Baekjae, and Shilla). The name Gaya has been recorded in various ways including Gaya, Gara, Gayang, Garak, and Imna.

According to the Memorabilia of the Three Kingdoms, the Gaya region encompassed the lower part of Nakdong River, southern coast, Mt. Jiri, and Mt. Gaya of today, generally including the western part of the Nakdong River at the Youngnam region. However, that was the situation right before the destruction of Gaya and according to the archeological discovery, Gaya was located widely throughout the eastern and western parts of the Nakdong River. It was also discovered that Gaya had an excellent culture based on the iron relics and that it had active trade relations with China and Japan.

Gaya formed alliances such as 5 Gaya, 6 Gaya, or Gaya 7 nations, Posang 8 nations, and Imna 10 nations to fight for supremacy against Baekjae and Shilla. Nonetheless, it disappeared from the history when the Great Gaya was unified with Shilla in 562 A.D.