A year after the battle, Muhammad and his followers returned to Mecca but were barred from entering until the following year. Hearing this, Muhammad continued to spread the word of Allah. He did this through verbal teachings and by sending his disciples, who had memorized the Quran, to various cities (over 50 of them were murdered by non-believers). The Prophet also sent letters to several kings inviting them to join the Islamic faith. Negus (ruler of Abyssinia and Bahrain), Emperor Heraclius and Chakrawati (Hindu king of Malabar) accepted Islam with many