Swaziland is a kingdom east of South Africa bordering Mozambique. It was founded by King Mswati in the 19th century and was originally larger than it is today. It was recognised as an independent kingdom by Britain during the Scramble for Africa but in 1903 it became a protectorate of the British Empire. In 1906 it was merged with Transvaal Province and 2/3rd of the land was assigned to Europeans and 1/3rd to non-Europeans with its own Swazi king. It was part of the Union of South Africa for decades, became a protected state after that and an independent kingdom in 1968.
Swaziland always used South African currency until the Lilangeni was introduced in 1974. It is part of the Common Monetary Area and as such pegged with ZAR, and South African currency is widely accepted in Swaziland next to their own currency.
Swaziland coins are a bit easier to find than Lesotho ones, but still not very common in bargain bins.
https://en.numista.com/catalogue/swaziland-1.html

