This is the history of the surname Liang that was extracted from the Chinese Classical book called Shi Ji (Historical Records).

Chinese surname No. 128 "Liang".
Liang means : a beam; a bridge; an elevation.
e.g. Qiao Liang means : the beams of a bridge.
Surname Liang is about 2600 years old.

Abstract:

The surname Liang originated in an area which was called the An Ding Prefecture during the Han Dynasty (206BC to 220AD).
An means : calm; still; quiet.
Ding means : tranquil; stable; fixed.
The present day location of An Ding4 Prefecture is in Gu4 Yuan2 county in Gansu province China.

King You (reigned 781BC to 771BC) was the 11th King of the Zhou Dynasty (1134BC to 250BC) who married a beautiful concubine called Bao Si. A year later she had a son who was named as Bo Fu.

In 773BC this beautiful concubine wanted her young son to become the crown prince and herself the official King's wife. She manipulated the old King and had the crown prince named Ji Yi Jiu banished to the State of Shen (present day Nan Yang city in Henan province).

The ruler of the State of Shen was the father of the King's wife. He was very angry, but there was nothing he could do as he was not strong enough to fight the Zhou Court.

In 771BC the ruler of Shen conspired with the Quan Rong, the non-Han Chinese from the north to attack the Zhou capital Hao (present day Xian city in Shaanxi province). The Zhou Court could not fight the combined army of the intruders. The capital fell to the invaders and was totally razed to the ground. The King, his beautiful concubine and the newly crowned young prince were killed in the turmoil.

Even though the capital was destroyed and ransacked, the Quan Rong did not not want to leave the capital. So the former crown prince Ji Yi Jin congregated an army from several vassal States to rescue the capital.

Knowing that his grandfather, the ruler of Shen, was still with the Quan Rong in the capital, the crown prince plotted with him and had the Quan Rong defeated and pushed them back to the north the desert where they belonged.

One of the generals who helped the crown prince to expel the Quan Rong was Qin Zhong whose son was called Kang who also helped to defeat the Quan Rong.

The crown prince, Ji Yi Jin was installed as King Ping who moved his capital to Luo Yang (present day Luo Yang city in Henan province) as the old capital was totally destroyed and uninhabitable.

The new King rewarded Kang with the title Hou (Marquis) which was inheritable. He also delegated Kang with authority to administer a district called Liang (present day Han city in Shaanxi province). Kang was known as Liang Kang Hou by the local citizens. He renamed his domain the State of Liang.

The State of Qin (present day Feng Xiang county in Shaanxi province) was a bordering State with Liang. Qin was a very powerful and bellicose State. It always wanted to expand its territory.

During the period of Spring and Autumn (722BC to 481BC). State of Qin decided to expand eastward. In 641BC it conquered and annexed Liang.

The descendants of Liang Kang Hou adopted LIANG as their surnames as in remembrance of their extinct State.

There is another version of the story of the origin of the surname. Apparently, according to this version, there are two sources of the Liang surname. The first part of the story is the same as version given above with a little more elaboration.

The 21st most common last name in China. There are two main sources of the Liang surname name.

1) Descendents of Bo Yi, the flood fighting helper of Xia Yu. During Zhou Xuan Wang’s reign, Bo Yi was ordered to conquer the west. Unfortunately, he failed and was killed. His five sons vowed to avenge and asked Xuan Wang to allow them to conquer the west. Xuan Wang approved, and gave them 7,000 well-trained soldiers. The five brothers were victorious over their avengers. Xuan Wang awarded land to the five brothers. The second son, Kang, was given land in Xia Yang of Liang Shan (Han Cheng in Shanxi province), and established the Liang kingdom. In 641 B.C. Qin Mu Wang eliminated Liang and the people began to bear the name of Liang afterwards.

2) The son of Zhou Ping Wang, Ji Tang, was awarded the land of Nan (south) Liang. His descendents also have the last name Liang.

Yet another version of the surname, extracted from Xungen.com is as follows;

Liang originated from the surnmae Ying, which is descended from the famous flood-control minister, Boyi, during the Dayu reign. Among Boyi's descendants was one named Fei Zi, who because of his ability to rear houses, was conferred the land of Qin by King Zhouxiao, regained the surname Ying and was known as "Qin Ying". Fei Zi's great-grandson, Qin Zhong was ordered by King Zhouxuan to conquer Xirong. He lost the battle and was killed. However, his five sons, with a seven thousand troop, continued his mission and were successful. King Zhouping conferred on Qin Zhong's youngest son, Qin Kang, the Xiayang Mount Liang where he established the Liang Kingdom. He was known as "Liang Bo" because of his high post. The Liang Kingdom was later destroyed by the Qin Kingdom and the Liang royal members escaped to the Jin Kingdom where they used their nation's name as their surname.

During the Spring-Auttumn period, there were officials named Liang Yi ,and Liang Hong in the Jin Kingdom and there was a doctor named Liang Gonghong in the Chu Kingdom. They all had the surname Liang because the places they lived in contain the Liang character (eg. Liangcheng, Gaoliang, Quliang).

The son of King Zhou Ping, Ji Tang was transferred to Southern Liang. Thereafter, his descendants took Liang as their surname.

During the Northern Wei era, when King Xiao Wen settled in Luoyang, he changed the Balie clan to Liang Clan. The Liang clans were mainly located in Shanxi, Hubei and Shandong. Later, during the Western Han period, the Liangs moved to Gansu and during the Western Jin period, to Zejiang and Guangxi. During the Eastern Jin times, the Liang Clan started settling in Fujian and towards the Tang Dynasty, the Liangs spread to Hebei, Qinghai, Sichuan and Hunan. At the end of Tang Dynasty, when Anshi was in chaos, the people of Liang moved to Guangdong. During the reign of Emperor Kangxi (Qing Dynasty), the Liangs emerged in Taiwan. The Liangs were mainly located in Anding, Tianshui, Henan, Hedong, Fufeng, Qiantang, Hepu, Luhun, Shunde and Ninghua.