Complex sentence: Development of the vehicle is started in the 70's of the 20th century, when China purchased a small quantity of heavy German Mercedes Benz 2060th Vehicles were used as artillery tractor for heavy guns.
Split into simpler sentences: Development of the vehicle started in the 1970's, when China purchased a small quantity of heavy German Mercedes Benz 2060th Vehicles. These were used as artillery tractor for heavy guns.