King Souligna Vongsa reigned for 57 years during which Laos experienced "The Golden Age" with regard to territory, prestige and power.
The Jesuit Giovanni Maria Leria arrived in Vientiane at the same time as the Dutch merchants 1641 and received the first European envoys into Laos.
Despite the disruptions that spanned the period from Setthathirath's death to Souligna Vongsa's ascension, Lan Xang, as Laos was called, apparently recovered very quickly.
John Philip de Marini, who recorded and published Leria's visit, noted that monks went from Siam to Laos "as to University."
With King Narai of Ayutthaya, he built the Phra That Si Song Rak (Stupa of the Affectionate Two) at Dan Sai (now in Loei province of Thailand) to commemorate their friendship and set the boundary of their kingdoms.