900 Vikings discover Greenland. 906 Annam (central Vietnam) attains independence from China. 912 Vikings and their leader, Rolo, become Christians. 925 First dyers guild established. 927 Prince Caslav Klonimirovic drives out Bulgarians, uniting (what today is) Serbia, Montenegro, Herzegovina and Bosnia to found Serbia. Orthodox Christianity is introduced as the state religion. 950 Córdoba, Spain [...]