By the Three Thrones

"By the Three Thrones" is a traditional saying across Macalgra, most common among sailors, navy-men and merchants who ply the way between distant ports. The saying refers to the Three Thrones of the three major empires - the White Throne of the Sarimarcus Empire, the Jade Throne of Liang and the Black Throne of the Sura Empire.
A variant of the saying is By the Three Thrones and the Columns, referencing the famous columns of the Royal Palace of Juventius.
The saying is slang for a very serious promise. After the Treaty of the Three Thrones over conduct at sea was signed in 3001 YSB, the title of the treaty was co-opted. It arose due to swearing on the gods proving of little use with the many disparate religions or total lack of religion common among traders and navy-men.