The act seal of Prince Vsevolod Mstislavich was the first material evidence found in the region of stable relations between the Prussian tribes and the Russians of the Northwest. Researchers have found evidence of this fact earlier, including in chronicles.

This item was discovered during the work of the Sambia archaeological expedition of the Institute of Archaeology of the Russian Academy of Sciences in 2016. The seal was found near the village of Privolnoye in the Zelenogradsky District. Traces of a rich settlement of the ancient Prussians were discovered there. Among the finds were pieces of amber, bronze and silver jewelry, parts of clothing, silver coins, fragments of pottery, a lead seal, and a bronze cross.

“Rossiyskaya Gazeta” in August 2016 quoted the head of the expedition Alexander Nikolayevich Khokhlov,

The obverse side of the rounded act seal depicts the scene of the Annunciation of the Blessed Virgin Mary; one can distinguish the figures of the Virgin Mary and the Archangel Gabriel, the patron saint of Prince Vsevolod Mstislavich. On the reverse side an impression was made of a full-height image of a holy warrior, the Great Martyr Theodore, the patron saint of the prince’s father. The warrior holds a spear in his right hand and a shield in his left.

Prince Vsevolod Mstislavovich of Novgorod (1117–1136) and Pskov (1137–1138) came from the dynasty of Rurikids. He was the eldest son of Grand Prince of Kiev Mstislav (Theodore) Vladimirovich by marriage with Christina, daughter of Swedish king Inge the Elder, and also the eldest grandson of Kiev prince Vladimir (Vasily) Vsevolodovich Monomakh.