South-East Asia and India under names similar to China (cf. e.g. Cina in modern Malay). Meanwhile, in China itself, people usually referred to the realm in which they lived on the name of the ruling dynasty, e.g. Da Ming Guo ("the kingdom of the Great Ming"), or as the Middle Kingdom or Central Kingdom (Zhongguo 中國); see also Names of China for details. When the Portuguese reached South-East Asia (Afonso de Albuquerque conquering Malacca in 1511) and the southern coast of China (Jorge Álvares reaching the Pearl River estuary in 1513), they started calling the country by the name used in South and South-East Asia. It was not immediately clear to the Europeans whether this China is the same country as Cathay known from Marco Polo. Therefore, it would not be uncommon for 16th-century maps to apply the label China just to the coastal region already well known to the Europeans (e.g., just Guangdong on Abraham Ortelius' 1570 map), and to place the mysterious Cathay somewhere inland. It was a small group of Jesuits, led by Matteo Ricci who, being able both to travel throughout China and to read, learned about the country from Chinese books and from conversation with people of all walks of life. During his first fifteen years in China (1583–1598) Matteo Ricci formed a strong suspicion that Marco Polo's Cathay is simply the Tatar (i.e., Mongol) name for the country he was in, i.e. China. Ricci supported his arguments by numerous correspondences between Marco Polo's accounts and his own observations: The River "Yangtze" divides the empire into two halves, with nine provinces ("kingdoms") south of the river and six to the north; Marco Polo's "Cathay" was just south of "Tartary", and Ricci learned that there was no other country between the Ming Empire and "Tartary" (i.e., the lands of Mongols and Manchus). People in China had not heard of any place called "Cathay". Most importantly, when the Jesuits first arrived to Beijing 1598, they also met a number of "Mohammedans" or "Arabian Turks" – visitors or immigrants from the Muslim countries to the west of China, who told Ricci that now they were living in the Great Cathay. This all made them quite convinced that Cathay was indeed China. China-based Jesuits promptly informed their colleagues in Goa (Portuguese India) and Europe about their discovery of the Cathay–China identity. This was stated e.g. in a 1602 letter