Harvard's series below is relatively short, with each volume about 300 pages on length
A much larger & more indepth series is Cambridge's History of China, which consists of 17 books (15 volumes). Each book is over 700 pages long
As an introduction to Chinese history, I would recommend Harvard's series on China's dynasties (I've read all except the Ming book)
Each volume examines the dynasty's rise, economy, social & cultural life, wars & rebellions and fall
Each one is about 300 pages, easy to read