When the Spanish expedition of Hernando de Soto crossed the Mississippi River on June 28, 1541 (June 18 on the Julian calendar, which was used at the time), it entered what is now Arkansas. It spent the next 11 months roaming around the state until de Soto s death on May 31, 1542 (May 21 on the Julian calendar). After his death, the survivors made their way to Mexico.