The issue is simple - it is a fantasy culture in the current form.
With all due regard to Ryazan, it is a common sense that it wasn't a center of a separate Slavic tribe. As influential as it was, it was burned down by Mongols... and not restored to it's former glory.
But this aside, I want to put your attention on the real group of people which existed there Severians.
Or rather, a link between Severians-Sevryuks-Sayan groups.
In times of Rus' there existed Severians, one of the old East Slavic tribes. Their legacy pretty much left with its people once they politically lost independence and remained with a cultural group known as Sevryuki (russian wiki article here) which spread across most of lands of so-called "Ryazanian" culture... but well, not reaching Ryazan itself. Later it transformed to another part, more modern Russian ethnos "Саяны" (wiki article here in Russian), as a leftover.
This whole group, which can be effectively called Severian, was one of the East Slavic ethnoses that did not arise. It played a big role in the wars of Russia and Lithuania, with Severian principalities switching loyalty to Russia and starting a war there. And later those lands served a good role as a frontier against Hordes, with people (sevryuki) serving in Kursk and Belgorod.
The culture of Sevryuki essentially was assimilated later. After Commonwealth swallowed Severian lands, some time later Khmelnytsky Uprising broke out. As one of the results, Hetmanate came into control of those lands. Following roughly the border between Russia and Hetmanate, two different colonization waves came, with Ruthenians coming from Right Bank and Muscovites from Russia. This served as an ethnical line for the cultural and national divisions later and since about XVII-XVIII century Severians remained only as small sub-ethnic groups in the appropriate territories.
This is a story of a real culture that existed in 90% of Ryazanian culture area. I don't know what is meant under Ryazanian culture or what kind of a name is it. It is a mystery.
Hopefully it helps.
With all due regard to Ryazan, it is a common sense that it wasn't a center of a separate Slavic tribe. As influential as it was, it was burned down by Mongols... and not restored to it's former glory.
But this aside, I want to put your attention on the real group of people which existed there Severians.
Or rather, a link between Severians-Sevryuks-Sayan groups.
In times of Rus' there existed Severians, one of the old East Slavic tribes. Their legacy pretty much left with its people once they politically lost independence and remained with a cultural group known as Sevryuki (russian wiki article here) which spread across most of lands of so-called "Ryazanian" culture... but well, not reaching Ryazan itself. Later it transformed to another part, more modern Russian ethnos "Саяны" (wiki article here in Russian), as a leftover.
This whole group, which can be effectively called Severian, was one of the East Slavic ethnoses that did not arise. It played a big role in the wars of Russia and Lithuania, with Severian principalities switching loyalty to Russia and starting a war there. And later those lands served a good role as a frontier against Hordes, with people (sevryuki) serving in Kursk and Belgorod.
The culture of Sevryuki essentially was assimilated later. After Commonwealth swallowed Severian lands, some time later Khmelnytsky Uprising broke out. As one of the results, Hetmanate came into control of those lands. Following roughly the border between Russia and Hetmanate, two different colonization waves came, with Ruthenians coming from Right Bank and Muscovites from Russia. This served as an ethnical line for the cultural and national divisions later and since about XVII-XVIII century Severians remained only as small sub-ethnic groups in the appropriate territories.
This is a story of a real culture that existed in 90% of Ryazanian culture area. I don't know what is meant under Ryazanian culture or what kind of a name is it. It is a mystery.
Hopefully it helps.