The correct answer is - fertile soil.
The Great European Plain, also referred to as the Russian Plain, is dominated by lowlands, naturally covered with dense grasses, and is known for its fertile soil. Most of the soil in this large plain is has very rich and deep upper, humus layer. The reason for this is that the grasses that grow their die out each year, and as they die out they decompose very quickly, giving the soil a new layer of decomposed biomass each year.
Because of the properties of the soil, this the region of Europe that is heavily used for farming, mostly crops like the wheat, hops, and corn. The conditions are excellent for them, they do not take a lot of the soil, and also contribute to keeping the soil very fertile constantly with their decomposing roots and steams.
How long it stands is the independent variable
Portugal established trading activities in China in 1513 when Jorge Alvares arrived.
In 1517 the King sent a mission and created a trade center at Nei Lingding.
Portugal and Ming Dynasty relationship gradually expanded but was deteriorated when Simão de Andrade arrived at Guangzhou in 1519. He violated their customs and laws, so Chinese people reacted by killing several Portuguese in the streets.
In 1521 the Emperor Zhengde died and the Ming Court lost interest in having relations with foreign countries.
There were two battles:
In 1521, every Portuguese vessel was confiscated and Chinese defeated a Portuguese fleet at The First Battle of Tamao
In 1522, Martim Alfonso de Merlo Coutinho was sent to establish diplomatic relations but the Chinese defeated them at The Second Battle of Tamao.
The Chinese resisted any Portuguese attempt to return. But in 1535 Portuguese Port Traders were allowed to anchor ships in Macau´s harbors and they could trade. Finally, in 1537 the Portuguese establish a little Colony at Macau to be administered by Chinese authorities.
