Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Good Overview of Mongol Invasion

Kalka River 1223: Genghiz Khan's Mongols Invade Russia is an excellent overview of the first Mongol invasion of medieval Russia. It is quite different from most other Osprey books, since the majority is dedicated to the describing the armies and their weaponary. As a result the book gives one a more indepth look at aspects other than the battle. While the 40 pages or so dedicated to the armies does not do either justice, it is a very good beginning.Where the book falls off is in the description of the battle. One would surmise that the lack of a full description is caused by the lack of information. However, this is a minor matter.