It was a year of 1979, when in Minneapolis, USA - Magnum Research Inc. was founded :) There were 3 people in the begining. Three very determined persons, and their objective was very clear, to develop an entirely new semi auto handgun around the very popular .357 magnum revolver cartridge. Working name of the project "Magnum Eagle". "Fathers" of the gun are J. Lindig, J. Skildam and H. Z. Skildam, founders of the company, also B. White - technological details and development. Originally gun was designed for target, silhouette shooting and hunting.
The first working prototype was ready by 1981, however problems with cycling/feeding made MRI to look for outsiders help. Such help was soon found - IMI(Isreaeli Military Industry). So in 1983 the first Desert Eagle was produced & sold, chambered for .357 magnum. Later the much more powerful .44 magnum DE was produced, by 1987 the .41 Mag round appeared, unfortunately this promicing round later was abandoned. In 1991 desert eagle was introduced in very mighty .50 Action Express caliber, designed by Evan Wilding, rebated case, base .44 magnum, which made very easy to interchange barrels between .44 .50 AE calibers. Finally the latest but hopefully not the last .440 Cor-Bon (Cor-Bon round, necked down .50 AE, for more info about this round read in .50 AE vs. .440 Cor-Bon) was produced in 1998.
P.S. Special thanks goes to Andrey Nazarow for the information & help. If you read Russian you'll find very interesting his FAQ Server RU.Weapon.