The Bunyoro-Kitara kingdom in Uganda, says it is suing the UK for alleged atrocities committed by its soldiers during the colonial period.
King Solomon Gafabusa Iguru I wants his people's land back
A spokesman for the Kingdom Ernest Kizza told the BBC they are seeking £3trillion ($5,500bn).
Mr Kizza said they will present written evidence at the International Court in the Hague to prove their case.
He also said that the UK colonial authorities took their land and gave it to a rival kingdom.
Kingdoms in Uganda were banned in 1966 but 10, including Bunyoro-Kitara, were restored when President Yoweri Museveni came to power in 1987.
"Bunyoro was one of the richest kingdom's in Africa that was plundered and destroyed. Until now the population is in poverty," Mr Kizza told the BBC's Network Africa programme.
He said they have letters written to the Queen of England by military officers informing her of the number of families and animals destroyed in the invasions.
The western Ugandan Bunyoro-Kitara kingdom resisted the British but was conquered after the rival Buganda kingdom joined hands with the British.
Mr Kizza said they also intend to sue the Buganda kingdom and the Uganda government to recover their land lost following the invasion.
He said the British government signed an agreement with the Buganda kingdom in 1900 allowing them to take over land belonging to the Bunyoro-Kitara kingdom.