The United Kingdom officially united on May 1st, 1707. England and Scotland were the first two to join the United Kingdom.
Pergamum
He did
Isabella and Ferdinand's major goals were to create wealthy kingdoms and to spread Catholicism. They also attempted to unite their kingdoms under Catholicism but were unsuccessful.
The Persian Empire.
Persian
His father had a dream to unite the city-states. Shortly after he died so Alexander was his heir. Alexander took his father's dream and tried to unite the Greeks, the Persians, and the Macedonians. He failed
A marriage between the queen of Castille and the king of Aragon.
King Narmer
Russia, Scotland, Serbia, England, Khazars -> Golden Horde
Use economic measures to unite the country.
The Hellenistic kingdoms
They remained independent.