Question: When was the peak of the conquest of the country that, during the Yuan dynasty, had extensive contacts with the country of the person who described evaporation?

<P0-S0> The late Turrell V. Wylie, a former professor of the University of Washington, and Li Tieh-tseng argue that the reliability of the heavily censored History of Ming as a credible source on Sino-Tibetan relations is questionable, in the light of modern scholarship. <P0-S1> Other historians also assert that these Ming titles were nominal and did not actually confer the authority that the earlier Yuan titles had. <P0-S2> Van Praag writes that the "numerous economically motivated Tibetan missions to the Ming Court are referred to as 'tributary missions' in the Ming Shih." <P0-S3> Van Praag writes that these "tributary missions" were simply prompted by China's need for horses from Tibet, since a viable horse market in Mongol lands was closed as a result of incessant conflict. <P0-S4> Morris Rossabi also writes that "Tibet, which had extensive contacts with China during the Yuan, scarcely had diplomatic relations with the Ming." <SEP> <P1-S0> the yuan undertook extensive public works. <P1-S1> among kublai khan's top engineers and scientists was the astronomer guo shoujing, who was tasked with many public works projects and helped the yuan reform the lunisolar calendar to provide an accuracy of 365.2425 days of the year, which was only 26 seconds off the modern gregorian calendar's measurement. <P1-S2> road and water communications were reorganized and improved. <P1-S3> to provide against possible famines, granaries were ordered built throughout the empire. <P1-S4> the city of beijing was rebuilt with new palace grounds that included artificial lakes, hills and mountains, and parks. <P1-S5> during the yuan period, beijing became the terminus of the grand canal of china, which was completely renovated. <P1-S6> these commercially oriented improvements encouraged overland and maritime commerce throughout asia and facilitated direct chinese contacts with europe. <P1-S7> chinese travelers to the west were able to provide assistance in such areas as hydraulic engineering. <P1-S8> contacts with the west also brought the introduction to china of a major food crop, sorghum, along with other foreign food products and methods of preparation. <SEP> <P2-S0> Han-era astronomers adopted a geocentric model of the universe, theorizing that it was shaped like a sphere surrounding the earth in the center. <P2-S1> They assumed that the Sun, Moon, and planets were spherical and not disc-shaped. <P2-S2> They also thought that the illumination of the Moon and planets was caused by sunlight, that lunar eclipses occurred when the Earth obstructed sunlight falling onto the Moon, and that a solar eclipse occurred when the Moon obstructed sunlight from reaching the Earth. <P2-S3> Although others disagreed with his model, Wang Chong accurately described the water cycle of the evaporation of water into clouds. <SEP> <P3-S0> Kolmaš writes that, as the Mongol presence in Tibet increased, culminating in the conquest of Tibet by a Mongol leader in 1642, the Ming emperors "viewed with apparent unconcern these developments in Tibet." <P3-S1> He adds that the Ming court's lack of concern for Tibet was one of the reasons why the Mongols pounced on the chance to reclaim their old vassal of Tibet and "fill once more the political vacuum in that country." <P3-S2> On the mass Mongol conversion to Tibetan Buddhism under Altan Khan, Laird writes that "the Chinese watched these developments with interest, though few Chinese ever became devout Tibetan Buddhists." <SEP> <P4-S0> the mongol conquest of china was a series of major military efforts by the mongol empire to invade china proper. <P4-S1> it spanned six decades in the 13th century and involved the defeat of the jin dynasty, western xia, the dali kingdom and the southern song. <P4-S2> the mongol empire under genghis khan started the conquest with small - scale raids into western xia in 1205 and 1207. by 1279, the mongol leader kublai khan had established the yuan dynasty in china and crushed the last song resistance, which marked the onset of all of china under the mongol yuan rule. <P4-S3> this was the first time in history that the whole of china was conquered and subsequently ruled by a foreign or non-native ruler. <SEP> <P5-S0> Wang Chong (; 27 – c. 100 AD), courtesy name Zhongren (仲任), was a Chinese meteorologist, astronomer, and philosopher active during the Han Dynasty. <P5-S1> He developed a rational, secular, naturalistic and mechanistic account of the world and of human beings and gave a materialistic explanation of the origin of the universe. <P5-S2> His main work was the "Lunheng" (論衡, "Critical Essays"). <P5-S3> This book contained many theories involving early sciences of astronomy and meteorology, and Wang Chong was even the first in Chinese history to mention the use of the square-pallet chain pump, which became common in irrigation and public works in China thereafter. <P5-S4> Wang also accurately described the process of the water cycle.