Zaklady Mechaniczne URSUS (Ursus Mechanical Works) began in 1893 in Warsaw, making agricultural products. Their first tractor was built in 1922. In the 1950s, Ursus began building tractors used Zetor-based designs, with great success. In the 1970s, Ursus entered into a licensing arrangment with Massey Ferguson for tractor designs.
Ursus - official site