If we suppose that Rurik came from the island of Rujan, then the inconsistencies between the three sources are significantly smoothed out since in this case Rurik is at the same time a Varangian from across the sea and a Slav living near Prussia. Some historians are inclined to this version. In this scenario Eastern Russia simply invited a Varangian (Viking) ruler from Western Russia. Understandably he became "legitimate" in both parts of Russia and therefore was able to unite the Eastern Slavic principalities with some Western ones into a single state.
Before the collapse of the Soviet Union, the Russian artist Ilya Glazunov was suddenly irresistibly drawn to visit the island of Rujan during his stay in the Western German Republic. At that time the students of the University of Berlin were conducting archaeological excavations there. He learned from them that a few days ago they had dug up a Slavic wooden boat of the IX century. Then Glazunov asked the archaeologists what other artifacts they found and received a somewhat irritated response from a Teuton which was forever etched into his memory: “Everything to magma here is Slavic!.." In Berlin Glazunov told about this to the deputy professor Herman. "I can tell you that in the Western Germany we have a huge warehouse full of Slavic artifacts and the ancient books written in Old Slavonic. After the end of the [Second World] War we took a lot of things to this vault and so far no one has been digging in it. <…> None of your Soviet or our scientists showed any interest in this." – the professor replied. Glazunov wrote about his trip in his book "Russia Crucified".4
"The map of the placement of the West Slavic tribal unions of the Bodrichs (Obodrits) and Lyutichs (Velets) in the VIII—X centuries", by Vladislav Matveev (p.n. Trevbus) taken from the website https://commons.wikimedia.org under CC license.
It is worth noticing that there was also another Slavic union of several tribes called the Obodrits (Bodrichs) living not far from both the island of Rujan (Rugen) and Prussia on the mainland.5 In the 16th century an Austrian baron Sigismund von Herberstein, the ambassador to Moscow, wrote a book about Russia. He outlined the then generally accepted history of the emergence of the Russian state in medieval Europe. According to it the Varangians came from the Vagria region in northern Germany. Then it was inhabited by the union of Slavic tribes of the Obodrits (Bodrichs). The center of all Vagria was Stargard (Stargrad). After the capture by the Germans it now bears the name Oldenburg, which means the same thing in translation – the Old Town, that is Stargrad. And the capital of the tribe of the Obodrites in Vagria was Veligrad (Wiligrad, Lat. Magnopolis). This city is mentioned under the year 965 in the work of the Arab author Ibrahim Ibn Yaqub 6 (at the end of the X century captured by the Germans and renamed to Mecklenburg). In the east, the Obodrites had founded Novgorod even earlier. When the inhabitants of Novgorod had discord they naturally turned to their ancestral homeland with a request to send them an authoritative prince. So Rurik and his brothers arrived in Novgorod to reign. The Obodrites played a significant role in the history of Germany and Prussia taking part in many of their foreign and internecine wars. In the end the fate of the Rujans (Rugs) befell them – they gradually became culturally like Germans lost their independence, were converted to Catholicism and forgot their native language.
"The map of the location of the West Slavic tribal unions of the Bodrichs (Obodrites) and Lutiches (Velets) in the 8th-10th centuries" by Vladislav Matveev (under the pseudonym Trevbus) taken from the site https://commons.wikimedia.org under the CC License.
Now let have a closer look at the Prussians. As proved by Lomonosov, in ancient times the Slavs formed a single Russian-Prussian tribe. When the Prussians separated into a separate ethnic group and became "independent", other Slavic tribes continued to live right next to them. Among them were those who continued to consider themselves Slavs – not only the Rujans and Obodrites already mentioned above, but also others, shown in the map (colored).
In pagan times a significant part of "independent" Prussia was again subordinated to Russia. The regions of Prussia, which directly bordered Russia at that time were inhabited by Prussians and Jews. Since 983, after the successful campaign of Prince Vladimir Krasno Solnyshko (Vladimir Red Sun), these areas of East Prussia were again listed among the Russian possessions. Apparently not for long, since in 1037-1038, the Grand Duke of Kiev Yaroslav Mudriy (Yaroslav the Wise) made a campaign against the Yatvyags as part of a large several-year Russian offensive in the western directions. 7
The Prussians willingly went to the service of the Russian princes. In 1215 the Prussian combat detachment acted on the side of the freedom-loving Novgorod boyars’ veche (a parliament of the nobles) in their struggle with their prince as a striking military force8. In Novgorod, one of its most ancient streets was inhabited by Prussian settlers and even bore the name “Prussian” (now Zhelyabov Street). So, the Prussians lived on the Russian soil since ancient times.
In 1225-1226 the Polish Prince Konrad Mazowiecki turned to the German Teutonic Order to protect against military incursions of pagan Prussians into the lands of Catholic Poles (although the Poles themselves committed predatory campaigns against Prussia). In 1230 the Papal curia approved the Teutonic Order for the conquest of Prussia issuing a special papal bull. Pope Gregory IX addressed the knights in it: "Gird up and be courageous and ready to fight with these pagans who have gathered to destroy us and our holiness; it is better to die in battle than to see the calamities of our people and the sanctity.9" Of course there was no threat from the Prussians to the Catholic world, it was pure propaganda. As a result of four difficult crusades stretching over half a century from 1231 to 1283 the Teutonic Order with the support of Poland eventually conquered Prussia piece by piece.
The map of the "Principality of late Kievan Rus" by SeikoEn, processed by the user Das steinerne Herz, taken from the Swedish site https://sv.m.wikipedia.org under the CC license.
The Prussians regularly raised uprisings and at one time the power of the order hung by a thread. But the Teutons won over the majority of the Prussian nobility by granting them privileges and was able to hold on. Since the Prussians put up such fierce resistance and did not belong to the peoples of the German group, they were subjected to almost total extermination and displacement outside their lands. The South Russian Chronicle reports on the mass migration of Prussians expelled by the Germans to the lands of Northwestern Russia in 1276-1277. 10
After the final conquest of Prussia by the Teutons in 1283, the second even greater wave of migration of Prussians to the Russian and Lithuanian principalities surged. The main areas of resettlement were the Novgorod, Pskov, Galician-Volyn principalities and Lithuanian Rus. It is no coincidence that more than 70 notable Russian noble families (including the Romanov royal family which Peter-I the Great belongs to) trace their ancestry from immigrants from ancient Prussia. In their ancestral coats of arms there are corresponding symbols – a crown as a sign of origin from the legendary kings of Prussia, two crosses signifying the conversion of the Gland-Kambila and his descendants to Orthodoxy and a pagan oak. In some coats of arms there is a generic symbol of the most ancient Prussian rulers – a black single-headed eagle with outstretched wings, clawed paws, sometimes with a crown on the neck. 11 Below is the Romanov family coat of arms which shows that not German but Slavic, essentially Russian blood coursed in the veins of Peter the Great.
4
Глазунов И.С. "Россия распятая", Издательство: АСТ, 2017 г., ISBN: 978-5-17-104398-8, 1008 С.
5
Boll, Ernst. Geschichte Meklenburgs mit besonderer Berücksichtigung der Culturgeschichte. Bd. 1, Neubrandenburg, 1855, S. 4. «Nach Adam hießen die Abodriten auch Reregen.»
6
Йоахим Херрман. Ободриты, лютичи, руяне // Славяне и скандинавы: Сб. – М., 1986. – С. 338.
7
Лаврентьевская летопись // Полное собрание русских летописей. Т. 1. С. 35. СПб., 1846. Стб. 163.
9
Очерки истории Восточной Пруссии / Г.В. Кретинин, В.Н. Брюшинкин, В.И. Гальцов, и др. – Калининград: ФГУИПП «Янтарный сказ», 2002.
10
Ипатьевская летопись // Полное собрание русских летописей. Т. 2. С. 35. СПб., 1998. Стб. 886–887. Стб. 874–875.