Yellow River

The Yellow River, also known as Huanghe, is the second-longest river in China and the sixth-longest river system on Earth, with an estimated length of 5,464 km (3,395 mi) and a drainage basin of 795,000 km² (307,000 sq mi). Beginning in the Bayan Har Mountains, the river flows generally eastwards before entering the 1,500 km (930 mi) long Ordos Loop, which runs northeast at Gansu through the Ordos Plateau and turns east in Inner Mongolia. The river then turns sharply southwards to form the border between Shanxi and Shaanxi, turns eastwards at its confluence with the Wei River, and flows across the North China Plain before emptying into the Bohai Sea. The river is named for the yellow color of its water, which comes from the large amount of sediment discharged into the water as the river flows through the Loess Plateau.

The Yellow River basin was the birthplace of ancient Chinese civilization. According to traditional Chinese historiography, the Xia dynasty originated on its banks around 2100 BC; Sima Qian's Shiji (c. 91 BC) record that the Xia were founded after the tribes around the Yellow River united to combat the frequent floods in the area. The river has provided fertile soil for agriculture, but since then has flooded and changed course frequently, with one estimate counting 1,593 floods in the 2,540 years between 595 BC and 1946 AD. As such, the Yellow River has been considered a blessing and a curse throughout history, and has been nicknamed both "China's Pride" and "China's Sorrow".

The Yellow River's basin presently has a population of 120 million people, while over 420 million people live in the immediate provinces which rely on it as a water source. The basin comprises 13 percent of China's cultivated land area. The area receives very uneven rainfall, only 2 percent of China's water runoff—water and sediment flow has decreased five-fold since the 1970s, and until recently, the river frequently did not reach the sea. Since 2003, China has been working on the South–North Water Transfer Project to alleviate the strain on the river's water supply.

When the Yellow River was still somewhat clear, it was simply referred to as 'the river' (河, Old Chinese: *gâi). Observations made at the Yumenkou gorge, where the river leaves the modern Loess Plateau, indicated the river changed to muddy sometime between 367 BC and 165 AD, according to chronicles' records. The alternative names 'murky river' (濁河, *drôk-gâi) and '(muddy) yellow river' (黃河, *gwâŋ-gâi) were attested in 145 BC and in 429 AD respectively. The name Yellow River fully replaces Murky River by the end of Tang dynasty, for unclear reasons.

In the Shaanxi loess plateau, it is referred to as 'river, my lord' (老爺河, [lo˦˩˨ i˧ xɤu̯˧]) in the Jin language. In Mongolian, it is called Šar mörön (Шар мөрөн 'yellow river') or Khatan gol (Хатан гол 'queen river'). The river is mentioned in the Kul Tigin stele as the 'green river' (Old Turkic: yašïl ügüz, 𐰖𐱁𐰞𐰽𐰺𐰍). The Tibetan name is "River of the Peacock" (Tibetan: རྨ་ཆུ, Wylie: rma.chu, THL: Ma chu; 玛曲; 瑪曲; Mǎ qǔ).

The Yellow River first formed sometime during the Late Miocene, Pliocene or Pleistocene, as a result of the Tibetan Plateau being uplifted.

The river has long been critical to the development of northern China, and is regarded by scholars as a cradle of civilization. Flooding of the river has also caused much destruction, including multiple floods that have resulted in the deaths of over one million people. Among the deadliest were the 1344 Yellow River Flood, during the Yuan dynasty, the 1887 flood during the Qing dynasty which killed anywhere from 900,000 to 2 million people, and a Republic of China era 1931 flood (part of a massive number of floods that year) that killed 1–4 million people.

The cause of the floods is the large amount of fine-grained loess carried by the river from the Loess Plateau, which is continuously deposited along the bottom of its channel. The sedimentation causes natural dams to slowly accumulate. These subaqueous dams are unpredictable and generally undetectable. Eventually, the enormous amount of water needs to find a new way to the sea, forcing it to take the path of least resistance. When this happens, it bursts out across the flat North China Plain, sometimes taking a new channel and inundating most farmland, cities or towns in its path.