Who is the longest-reigning monarch ever?

King Bhumibol of Thailand is usually thought of as the longest-reigning monarch in the world when he passed away at age 88 after holding the throne for 70 years. After his death the title seems to have passed on to Queen Elizabeth II of Great Britain who has held the throne for 65 years and still counting.

It is little known, though, that there are several other monarchs (with verifiable reigns by exact date) who had held their thrones much longer.

King Sobhuza II of Swaziland holds the longest verifiable reign of any monarch in recorded history at 82 years & 254 days. Bernhard VII, Lord of Lippe comes second at 81 days, 234 days. In fact, many others follow in the list before King Bhumibol who is placed at #17 (70 years, 126 days) and even longer before Queen Elizabeth II who is in #42.

Pepi II Neferkare of Ancient Egypt is said to have reigned for 94 years and Taejo of Goguryeo, a kingdom in Korea, is said to have reigned for 93 years. But these are monarchs whose exact dates of rule are unknown, the dates cannot be verified and therefore, disputed.