East Lothian is in the south east of Scotland. Historically, the area is a division of the ancient Celtic province of Lothian, the others being West Lothian and Midlothian, the three created as local government authorities. The name's earliest written form Lleudinyawn occurs in a 12th century Welsh poem but is probably much older. The meaning of the name is debated but may mean 'the land of Lleu's fortress.'

East Lothian has been inhabited by various peoples since the last Ice Age almost 10,000 years ago. Its earliest known structure, a Mesolithic hunter's dwelling dating to around 8,000 BC, was excavated recently at East Barns.

The earliest native people of East Lothian were called the Votadini, by the Romans who invaded Scotland in 79 AD. Votadini appears to be a romanised form of Gododdin, the name they used themselves. They were a Celtic people who spoke an early form of Welsh. They were restless under Roman rule so to control the area the legions built a fort at Inveresk Hill near Musselburgh.

In 1919 a fabulous horde of Roman silver dating to the 5th century was discovered during excavations at Traprain Law hill fort in the centre of the county. The fort was a principal stronghold of the Goddodin. It can be seen in the National Museum of Scotland in Edinburgh.

In the centuries following the Roman departure from Scotland in the early 5th century, the Goddodin disappear from history, eclipsed by the Northumbrians, who in turn vied with the Picts and Scots for control of this small but fertile part of Scotland. In national mythology the struggle produced Scotland's national flag, the St. Andrew's Cross or Saltire. It is said a cloud formation in the shape of a cross against a blue sky inspired a combined army of Picts and Scots to defeat a larger force of Northumbrians under their leader Athelstan in 832. The battle was waged near the village of Athelstaneford where a Saltire now flies in perpetuity to commemorate the event.

Scottish kings favoured the area. David I established Haddington as a royal burgh in the 12th century and William the Lion built a royal palace in the town where his son the future Alexander II was born. Haddington also boasts Scotland's oldest church, St Martin's, established by William's mother Ada but now ruinous. David I also introduced the feudal system to Scotland by granting lands to Anglo-Normans who established the castle as the principle means of defence.

The prosperity of the area suffered in the late 13th century and the first 30 years of the 14th century, when normal social and economic life was disrupted by the Wars of Independence with England. During the remainder of the 14th century, the Black Death and continuing intermittent war with English forces added to the area's woes and its burghs and ports suffered a serious decline until about 1500.

In the two centuries from 1500 to 1700 peaceful economic and social life was continually interrupted by wars and religious strife. The Protestant Reformation of the 1550s and 1560s, led in part by Haddington-born John Knox, initiated the decay and disappearance of many of East Lothian's medieval monastic buildings and churches. Wars continued to disrupt the county with further English incursions in the 1540s followed by the Covenanting and Cromwellian wars of the 17th century, when some of the county's greatest castles such as Tantallon and Hailes were ruined.

The more settled 18th and 19th centuries were periods of great change in agriculture and industry sweeping away most of what remained of medieval life in town and country. The old runrig system of land tenure, which had been disappearing since the late 17th century, was swept away, consolidated into large farms with fields enclosed by walls and hedges. Many of the peasants who had toiled under the old system left the land to work in the growing industries in the towns or were employed as farm workers. In East Lothian the great landowners, John Cockburn of Ormiston, Lord Belhaven and others, maximised the profits from their lands by introducing new crops, agricultural methods and industries.

The expansion of the coal industry, which had existed from medieval times, fuelled new industries such as potteries, brick works, salt extraction, brewing and distilling and powered the expanding rail network of the 19th century. Communications were dramatically improved with the introduction of turnpike roads in the 18th century together with extensive bridge building. One of the earliest railways in the world was built in East Lothian linking Tranent with Cockenzie in 1722 using wagons moved by horses (uphill) and gravity (downhill ) on wooden rails.

In the 20th century East Lothian was profoundly affected socially and economically by the two world wars. The extensive agricultural estates with their great houses were in decline before the Second World War, hit hard by heavy death duties and the 1930s economic depression. Many were demolished, others such as Newhailes survive as tourist magnets while a few succeeded in retaining some of their original role as the hubs of large estates.

Many of the industries which grew up in the 18th and 19th centuries did not survive long into the 20th, if at all. The Second World War gave a brief reprieve to heavy industries such as coalmining, but despite the development of open cast mining at Blindwells in the 1980s and 1990s, mining ceased to be a major employer when the last deep mine closed in 1964. The post-war fishing industry was never strong. Since 1945 there has been a shift to a service-based economy, generating broad social changes as former mining villages and fishing towns reinvented themselves to accommodate tourism or became, in part, dormitory communities for Edinburgh commuters.