Established in 1182, Lancashire is one of the youngest historic counties in England. Shortly after the Norman conquest, William the Conqueror gave the land between the Ribble and Mersey rivers to the norman Roger de Poitou, who owned it until his rebellion against King Henry I in 1102.
In the Domesday Book of 1086, the land that lay between the River Ribble and the River Mersey (Inter Ripam et Mersam) was included in the returns for Cheshire, while other parts of the land were treated as part of Yorkshire.
In the 12th and 13th centuries, many towns in Lancashire received market rights, which increased the region’s prosperity. In the Wars of the Roses (1455-1487) the noble houses of Lancaster and York fought for succession to the throne of England. These civil wars take their name from the coats of arms of the two houses, the white rose for York and the red rose for Lancaster. In the 19th and 20th century, the towns in the south of the county grew rapidly thanks to the Industrial Revolution, so that by 1971 the population of Lancashire (including all affiliated boroughs) had grown to over 5 million.