How long did the Vyshaanti struggle to control Ardeep?
Here's what the lore says, drawn directly from the indexed sources:
-10460 DR * Aryvandaar conquers Ardeep. Over the next century, the Vyshaanti struggle to keep it under control, and kill two of Ardeep's rulers, Ilitharath and his grandson Tarosspur.
Source: -10460 DR
-10600 DR * Third Crown War: Coronal Ynloeth dies in mysterious circumstances. Following this, Shantel Othreier is conquered by Aryvandaar ending the Third Crown War. Only the vassal realm of Ardeep holds out against the Vyshaan, though resistance movements spring up in Shantel Othreier and Miyeritar. * The Aelryth of Miyeritar believe Coronal Ynloeth's death to be a murder, and they launch a failed retaliatory strike against Tiru Orindraar.
Source: -10600 DR
-10900 DR * The Third Crown War begins when negotiations between Shantel Othreier and Aryvandaar break down and Aryvandaar attacks. * The Vyshaan lords of Aryvandaar gain a secret patron in Malkizid, a fallen solar.
Source: -10900 DR
-10300 DR * Keltormir withdraws its forces from its eastern territories and holds a defensive line at Highlands' Edge as a result of being trapped between the forces of the Vyshaan of Aryvandaar and Clan Hune of Ilythiir.
Source: -10300 DR