The Plano culture was the last group of prehistoric Native American people or Paleoindians that inhabited the American Southwest before the Archaic age. The Plano culture or plains people emerged with the end of the Ice Age in about 8000 BC.
End of the Ice Age
The end of the Ice Age brought the extinction of the big game hunted by the Paleoindians such as the mammoth and mastodon. The Caribou and Musk ox moved to the far North.  With this change the previous cultures called the Clovis and Folsum peoples had to change their lifestyle and hunting habits.
They became more distinctly hunter-gatherers and now used a different type of spear point and also looked for smaller animals such as deer, elk, and other small game, but continued hunting the largest game or Bison. (These extinct Bison had six foot horns and weighed up to 3000 pounds).  They hunted Bison on the plains and deer and elk in the forests.
Adaptation to a new environment
As the forces of nature changed the ecological nature of the environment, the Paleoindians adapted to their environment. In ancient times the end of the Ice Age caused the Laurentide Ice Sheet to recede to the North. The Boreal forest also moved North and was replaced by a deciduous forest. Eventually grasslands replaced the deciduous forest.  The melting of ice in the mountains caused the rivers to become wider. Now along with game there was more gathering of wild plants and berries, and fish and mussels.
The Paleoindians were hunter-gathering Indians that lived in North America about 12,000 years ago. They consisted of three separate groups that were characterized by their artifacts and tools. The Clovis culture is the oldest Paleoindian group that subsisted primarily on big game hunting with the mammoth being the most sought after big game. With the end of the Ice Age the mammoth and big game sought by the Paleoindians became extinct and therefore a new culture emerged: The Plano culture. 
Plano is the Spanish word for plains in North America.  The Plano people were the people of the plains. Their main way of hunting was mass extinction by driving a herd of animals usually Bison over a cliff and then finishing them off with spears or darts. They used the whole animal for food, tools, and clothing. Their extermination practice of hunting continued into the nineteenth century. 
The tools of the Plano culture were distinctly different than the Clovis culture tools. The Plano projectile points did not have flutes or grooves as did Clovis tools.  The tools being adapted now for the type of game and fish available.
The Plains occupied by the Plano culture extended from Canada down to the Gulf of Mexico. The area was between the Rocky Mountains and the Mississippi River and also included the Missouri River, the Arkansas River, and the Red River. 
The big game traditions of the Paleoindians and the Plano culture persisted longest in the Great Plains of the Southwest. 
The Plano culture was characterized mainly by the type of tools used; and its emergence was characterized by the ending of the Ice Age that caused environmental changes that affected the lifestyles of the previous cultures of that period: the Clovis and Folsum cultures.