It became dry and the warm climatic conditions damaged the steppes and green pasture lands which made the Mongols to move towards China.
Explanation:
The tree ring data provide the necessary historic information that the Mongolian steppes were in the grip of intense drought and the mongol tribes competed for survival in those dry climatic conditions which prevailed thousand years ago. But during 1211 -25 it is observed that Mongolia had experienced an unusual rainfall which filled the atmosphere with humidity and moisture.
This climatic conditions had made the dry steppes to fro into grasslands which fed the mongol' vital herds of horses. It is observed that every mongol had around five horses which paved way for creation of huge cavalry force of Mongol Army. this change in climatic conditions gave rise to Genghis khan to expand his first ever huge land empire.
The minimum land sale was set at one square mile (640 acres), and the minimum price per acre was $1. (Congress hoped to refill the treasury by land sales in this region, but the requirement of $640 in cash eliminated many potential buyers).
The Mayan writing system is different because, the ancient Maya system of writing has around 800 signs, and it's a mixture of logograms and phonetic signs.
