Among Schirren's papers in Riksarkivet there are two lists of travellers to and from Russia who passed the border post at Neuhausen (Vastseliina) during the period 1 January 1698 to 30 June 1699. Some examples:
8 January 1698: Lt. Col. Rohr and two servants from Köningsberg to Moscow.
10 January 1698: The wife of Colonel Blumbergh and her people & Lieutenant Johan Rickman.
30 May 1698: Lieutenant Johan Gordon and a servant from England to Moscow.
23 June 1698: The theology student Tobias Renner from Thuringia to Moscow.
7 July 1698: Johan Gordon, son of General Gordon, and his wife along with a captain and four servants from Scotland to Moscow.
Those travelling the other way were fewer in 1698, but one notable example:
21 October 1698: Guillaume Felle, a Doctor of Theology of the Franciscan Order from Persia to Mitau and France. (Felle was a noted traveller).
Source: Riksarkivet, Schirrens samling originalhandlingar, vol. 13