Unification started in 1902 and continued till 1932, when the modern-day Kingdom of Saudi Arabia was proclaimed under the leadership of Ibn Saud, creating what is sometimes referred to as the Third Saudi State.
The Korean Empire was the last independent unified Korean state. It stood until Japan’s annexation of Korea in August 1910.
Ugyen Wangchuck was the first Druk Gyalpo (King of Bhutan) from 1907–1926. In his lifetime he made great efforts to unite the country and gain the trust of the people.
The Austrian Empire was a Central European multinational great power from 1804 to 1867, created by proclamation out of the realms of the Habsburgs.
Founded by King Prithvi Narayan Shah, a Gorkhali monarch of Rajput origin from medieval India, it existed for 240 years until the abolition of the Nepalese monarchy in 2008.
The Emirate of Diriyah was established in the year 1744 when Muhammad ibn Abd al-Wahhab and Prince Muhammad bin Saud formed an alliance to unify the many states of the Arabian Peninsula.
Starting in the late 17th century, the Ashanti king Osei Tutu and his adviser Okomfo Anokye established the Ashanti Kingdom, with the Golden Stool of Asante as a sole unifying symbol.
The Kingdom of Dahomey was an African kingdom that existed from about 1600 until 1894. Dahomey developed on the Abomey Platea in the early 17th century and became a regional power in the 18th century.
The different Betsileo kingdoms (Fandriana, Fisakana, Manandriana, Isandra, etc.) existed independently of each other with oral traditions dating back to the 17th century.
The main reason for this rather unusual alliance between separate tribes was to react against slavery and wholesale murder and destruction wrought by the early Portuguese discoverers and colonisers of Brazil onto the Tupinambá people.