Historians do not agree on dating the beginning or end of the Great Game. One author believes that the Great Game commenced with Russia's victory in the Russo-Persian War (1804–13) and the signing of the Treaty of Gulistan of 1813 or the Treaty of Turkmenchay of 1828. Another believes that it began between 1832 and 1834 as an attempt to negotiate trade deals with Ranjit Singh and the Amirs of Sind.Hopkirk views "unofficial" British support for Circassian anti-Russian fighters in the Caucasus ( 1836 – involving David Urquhart and (for example) the "Vixen" affair – in the context of the Great Game.