During the years 900-1100 Khitan (Ancient Mongolian Tribe) was a huge threat to Goryeo (Korea). Khitan carried out 3 invasions in order to occupy the Korean Lands. During the time Goryeo had very strong relations with Song (China). This had always angered the Khitan as they were against this alliance since Song was also a big enemy to them. Goryeo beaches were raided by the Khitan and they built a large camp near the border fortresses. It is believed that they had attacked with an army 400,000-800,000. Goryeo was only able to resist for a few days. After Minister of Defence Heo-Sui had met with the Khan and agreed to hand over a poportion of the Goguryeo Lands over. By this way the Khitan had stoped the invasion. However this process was repeated twice more. Khitan was also able to dissolve the Song and Goryeo Alliance. 200,000-300,000 Goryeo warriors had lost their lives during the battles. Khitam was Goryeos biggest enemy.