Slavs have common origin to some extent, unlike Romance languages speakers. All Slavs probably can trace their roots back to pre-migration lands. Slavs have common myths and legends, not all Slavs have all the same ones, but there always some present in multiple Slavic nations. In the end we have and we had pan Slavic movements to bring us closer. Similarly to our languages, which slightly change from shade to shade as you go from North to South, our cultures slightly change. When you compare Russian and Czech cultures there are some noticeable differences, but when you go from Russia to Belarus, where does the Russian culture stop and Belarusian begins, same goes for Belarus and Poland, Poland and Czech republic etc. And last but not least, term Slavic Soul doesn’t exist without a reason.