Seolleongtang is typically simmered over a low flame over a period of several hours to an entire day, to allow the flavor to be gradually extracted from the bones. It has a milky off-white, cloudy appearance and is normally eaten together with rice and several side dishes; the rice is sometimes added directly to the soup.
In the Joseon dynasty, Koreans regularly made nationwide sacrifices to their ancestors, such as Dangun (the legendary founder of the kingdom of Gojoseon). The nationwide sacrifice was called Sŏnnongje (hangul: 선농제; hanja: 先農祭, Sŏnnong meaning "venerated farmer"), and the altar for the sacrifice was called Sŏnnong dan (hangul: 선농단; hanja: 先農壇), which dates back to the Silla Dynasty.
King Seongjong had visited the sacrifice himself, and had eaten a meal with the people of Joseon. To increase the food supply in Joseon, King Seongjong ordered them to invent dishes that could feed the maximum number of people using the least amount of ingredients, and seonnongtang (tang meaning "soup") was one of these.
Another historical opinion precedes the Joseon dynasty concerning the origin of seolleongtang. According to this, the food was originated by the Mongolian invasion of Koryo in 13 BC. Mongolian food "Sulen" is sliced and boiled beef with green onions, which developed into seolleongtang in Korea.
Seonnongtang is now called seolleongtang for easier pronunciation. The phonetic values have changed as follows:
The first change is a consonant liquidization making the two "N" sounds into softer "L" sounds for easy pronunciation. The second change is a vowel harmonization of the "O" sound affected by the "Ŏ" sound.
Among common misbeliefs related to the dish, the name may come from its snowy white color and hearty taste, so seolleongtang was named "雪濃湯" in hanja (literally "snowy thick soup"). Therefore, several Korean dictionaries say that the hanja spelling such as 雪濃湯 is an incorrect usage for the dish. Nevertheless, the misspelling is used to refer to the soup in hanja.