The spoils of war looted during the 'Deluge' continue to generate a lot of excitement. But not all objects stored in Swedish cultural institutions are of the same provenance - there are also many purchases or gifts. After all, the Vasa dynasty sat on the Polish and Swedish thrones for several decades.

The Polish-Swedish wars and the plundering of the Polish-Lithuanian Commonwealth, but also the common Vasa dynasty that reigned on the Polish and Swedish thrones, resulted in numerous contacts between the two countries, and thus also an exchange of objects. The collection of polonica in Sweden has still not been fully compiled, although there have been several attempts to catalogue them so far. A project is currently underway at the University of Warsaw to catalogue the first part of the war booty looted by the Swedish army during the 'Deluge' and the Great Northern War. Previous documentation and search efforts have usually been limited to a specific group of objects, usually books. However, it is important to trace the history of these searches.

Key here was paragraph 9 of the Peace of Oliva (1660), which stated: "All archives, public, municipal, court and clerical records, and the royal library which have been removed from the Kingdom of Poland and the Grand Duchy of Lithuania shall be returned from the Swedish side; this return shall take place at the time of the exchange of ratifications or at the latest three months after this exchange". What was at stake here was primarily the recovery of the royal book collections and also the Crown Metrics, i.e. the book of entries of documents coming out of the royal chancellery. The main difficulty with the recovery of book collections and archival records in the 17th century was that Godfryd von Schröder, sent to Sweden with the order to recover his looted heritage, was unaware of the number of objects he was seeking. Having acquired several chests of books and documents, including the Crown Metryka, which was crucial for the Poles, he returned to the Republic. The next attempt came during the reign of John III Sobieski; at that time a retinue of Szczesny Morsztyn was sent to Sweden, in which one of the Crown officers, Jakub Bernig (Bernik), was charged with finding books looted by the Swedish army during the 'Deluge'. Bernig returned with some of the books taken away in the mid-17th century.

Stanislaus Augustus Poniatowski sent Jan Chrzciciel Albertrandi to Sweden, whom he commissioned to obtain information about the Polish books there. At that time, for the first time, the search encompassed objects beyond book collections and archives, and did not only concern war booty. Albertrandi then prepared many volumes of copies and copies of original documents, which he took with him on his return journey.

His 19th-century explorations included a search for Copernicans and Warmians. These researches were conducted by, among others, the Toruń-born historian Leopold Prowe (1821-1887), Maximilian Curtze (1837-1903) and Ludwik Birkenmajer. In 1914, research was conducted by Eugeniusz Barwiński, Ludwik Birkenmajer and Jan Łoś. This was in response to the work done in 1852 by Beda Dudik (1819-1890), a Moravian historian who was searching for monuments of Czech literature looted by the Swedes during the Thirty Years' War; all the books and archives he found were published in "Forschungen in Schweden für Mährens Geschichte". During the expedition, the collections of libraries and archives in Uppsala, Stockholm, Lund, Linköping, Vestrås and Strängnäs, as well as Skokloster Castle, were examined and single archives hitherto unknown were found.

Further explorations in Sweden were carried out in 1955, commissioned by the Institute of History of the Polish Academy of Sciences, by Prof. Antoni Mączak and Prof. Marian Małowist. Their aim was to select archival items for microfilming. As a result of this expedition, Polish collections received, among others, microfilmed materials from the Extranea IX: Polen, Krigshistoriska Handlingar, Diplomatica or Riksregistraturet group. It should be noted, however, that due to limited funds, not all the material was copied at the time.