The Lothians is the collective name for the three counties of Midlothian, East Lothian and West Lothian in the Central Belt of Scotland. They're all lowland in nature, heavily populated around Edinburgh, and bounded to the north by the Firth of Forth, to the south by the Lammermuir hills. In ancient times Lothian was a province of Northumbria, becoming part of Scotland in 973 AD. There are half-a-dozen plausible sources for the name, which means no-one knows.
East Lothian is the most scenic of the city hinterlands. The coast is muddy near the city but improves as you go east. Then comes a "Costa Golf" of sand hills, ruined castles and pine woods; finally cliffs and craggy islets.