Navajo is spoken in the American Southwest (primarily Arizona, New Mexico, and Utah) by the Navajo people, or Dine'. The largest of all the Native American tribes, the Navajo are one of the few tribes that still use their native language in everyday communication. The Navajo language first appeared in writing in the mid-1800s. In 1939, the alphabet was standardized and printed materials were available. Shortly after, during World War II, bilingual "code talkers" sent secure radio messages using Navajo as a code. Includes over 9,000 entries; a detailed section on Navajo pronunciation; and useful, everyday expressions.