Today there are two remaining Baltic nations- Latvians and Lithuanians. But in 13. century there was a third tribe living in present-day Kaliningrad oblast in Russia and Poland. They were Prussians- Pruzzen in German. Prussians encountered the German Crusader aggression first and fought for a long time, but lost their freedom and became assimilated. Today are no real Baltic Prussians in Kaliningrad just as there is no German Prussians in there. The Prussian nation became extinct at the result of the Crusade.
Just as the Early Latvians Prussians were not unified nation but were divided in various smaller tribes and tribal areas. The areas were called laūks– field, common to Latvian word lauks meaning the same. Laūks included fortifications and villages. Village was called kāims. Since the Prussians newer formed a united nation, they called them selves based on the names of regions from where they came from like Galindians, Sambians, Bartians, Nadrovians, Natangians, Scalovians, Sudovians. Chronicon terrae Prussiae (The Chronicle of the Prussian Land) is the prime source about the Old Prussians. The author Peter of Drusburg list eleven lands and ten tribes in Prussian region.
The Old Prussians were Pagans and this made the vulnerable to attempts of baptizing. Polish king Boleslaw I sent Adalbert of Prague to baptize the Prussian pagans. But in 977. he was murdered by locals. This was a large shock to Catholic Europe and Adalbert became a martyr and saint. His death triggered numerous Polish attempts to conquer Prussians. In 1124. Poles attacked the Prussians of Pomerania. In 1147. Poles attacked Prussians for their involvement in inner Polish struggle. In 1200s Prussia became as field of interest for German knights. Since Poles could not conquer Prussians and force them to baptize the Pope of Rome issued the Christian of Olivia to mission of baptizing Prussian pagans. He became the first bishop of Prussia. Order of Dobrzyń was created to persuade Crusade to Prussia, but it was short lived and joined the Teutonic Order. In 1224. Emperor Frederick II declared Prussia as part of Holy German Empire of Rome. The key land holder was to be Teutonic Order who was subjected to the Pope and Empire and made there their own monastic state. In 1233. the attack of 21,000 Teutonic Knights begun. They were also assisted by Poles and other German vassals. Prussians resisted fiercely, but Crusaders were too strong, in 1286. a large rebellion took place but were stopped by Crusaders. Prussians received the Lithuanian support but it was not enough. Teutonic Order established a strong base of operation downsizing the Prussian rebellion. Order supported colonization of Prussia making Prussians exposed to assimilation. A large influx of German and Polish immigrants settled in Prussia in next centuries. Prussians were forced to live in slavedom and slowly they lost their national identity and language. In 18. century the language became extinct. But thanks to German scholars and Clergyman who translated various works such as Bible in Prussians, the linguistics can record Old Prussian language. Some old Prussian poems also have persisted until this time.
Today is hard to tell whether the Baltic Prussian still exist. Surely they all have predecessors living in Germany, Baltic States or other places. After East Prussia was ceded to Soviet Union the ethnic cleaning took place and almost all German population was deported to East Germany. So there is small chance to find Prussians in Kaliningrad, but rather in Germany where there is many organizations calling them Prussians. Such organizations also exist in Baltic States. Today according to Latvian encyclopedic claims there are 100,000 people calling themselves Prussians.