From the back of the book:

In the year 2750, humanity was in the midst of a golden age. United under the interstellar government of the Star League, all mankind prospered and enjoyed an improved quality of life made possible by advances in tehcnology, commerce, human rights, and the arts. Humanity had truly inherited the stars. But those some advances also carried a curse, for the engines of war from the Star League era possessed power unequalled in the Successor States today.

BattleTech Technical Readout: 2750 provides illustrations, statistics, and other vital information about the BattleMechs, AeroSpace Fighters, Tanks and Hovercraft, Personal Equipments, and combat JumpShips of the Star League.