The Arikara also known as Sahnish, Arikaree, Ree, or Hundi, are a tribe of Native Americans in North Dakota. Today, they are enrolled with the Mandan and the Hidatsa as the federally recognized tribe known as the Mandan, Hidatsa, and Arikara Nation.

Linguistic divergence between Arikara and Pawnee suggests a separation from the Skidi Pawnee in about the 15th century. The Arzberger Site near present-day Pierre, South Dakota, designated as a National Historic Landmark, is an archeological site from this period, containing the remains of a fortified village with more than 44 lodges.

An Arikara village, near where present-day Pierre, South Dakota developed, was visited in 1743 by two sons of the French trader and explorer La Vérendrye.

In the last quarter of the 17th century, the Arikara came under attack from the Omaha/Ponca and the Iowa near the end of the Omaha/Ponca migration to Nebraska. With peace established later, the Arikara influenced the newcomers. The Omaha still credit the Arikara women for instructing them in the art of building earth lodges.