With the death of Thánh Tông in 1497, the Dai Viet kingdom swiftly declined. Climate extremes, failing crops, regionalism and factionism tore the Vietnamese apart. From 1533 to 1790s, four powerful Vietnamese families: Mạc, Lê, Trịnh and Nguyễn, each ruled on their own domains. In northern Vietnam (Dang Ngoai–outer realm), the Lê kings barely sat on the throne while the Trịnh lords held power of the court. The Mạc controlled northeast Vietnam, Trà Kiệu and sometimes the Cambodian court. The Nguyễn lords ruled the southern polity of Dang Trong (inner realm). Thousands of ethnic Vietnamese migrated south, settled on the old Cham lands. European missionaries and traders from the sixteenth century brought new religion, ideas and crops to the Vietnamese (Annamites). By 1639, there were 82,500 Catholic converts throughout Vietnam. In 1651, Alexandre de Rhodes published a 300-pages catechism in Latin and romanized-Vietnamese ("chu quoc ngu") or the Vietnamese alphabet.