United Baltic Duchy ended in 1918.
Duchy of Savoy ended in 1713.
The Grand Duchy of Moscow.
A duchy is the jurisdiction of a Duke. You'd have to check out the specific duchy for more detailed information. A good place to start is the British Royalty website.
The Baltic Sea.
Since the first duke of England was the Duke of Cornwall, the son of Edward III, 1337, I'm going to assume that the first Duchy would be the same, Duchy of Cornwall. The Duchy of Lancaster is held by the Soverign. in Lancaster the toast, "To the Queen, Duke of Lancaster" that's "Duke" not Duchess.
United Baltic Duchy was created in 1918.
Duchy of Bytom ended in 1498.
Duchy of Burgundy ended in 1477.
Duchy of Carinthia ended in 1919.
Duchy of Carniola ended in 1918.
Duchy of Florence ended in 1569.
Duchy of Friuli ended in 828.
Duchy of Warsaw ended in 1813.
Duchy of Brzeg ended in 1675.
Duchy of Belz ended in 1462.
Duchy of Teschen ended in 1918.
Duchy of Lithuania ended in 1413.