When did kurini and palanky of Zaporozhian Sich arise?

For the first time the word "kurin" (temporary accommodation) to define the Cossack unit was introduced by B. Khmelnytsky. When he revived Chortomlytska Zaporozhian Sich (1652-1709), instead of the first Zaporozhian (Bazavlutska) Sich, which was destroyed by the Poles in 1638, he built on the Bottom of the Dnieper 5 outposts-palankas, formed 40 kurins (500 Сossacks in each one) and determined Kosh of the Sich as place of permanent stationing for them. The question, put as the title of the article, worried several generations of historians and amateurs, interested in Cossack history, by only now thanks to our research we have concrete reply to this question. Why previous historians couldn't find the answer? First – they didn't know, when, where, at what circumstances and with what organizational structure first Zaporozhian Sich emerged. Second – some modern professional historians don't understand, that absence of sources can be compensated by usage of modern new methods of research, from other sciences as well, which enable to get indirect information on the topic. Only combination of traditional and modern approaches in studies helps to make them successful. Third, faulty view on the process of appearance and development of Ukrainian Cossacks still dominates. Everyone knows idea of Aristotle, that we can understand the essence of things only when we know their origin and development. Let me remind that Ukrainian Cossacks were military formation. Hence, process of Ukrainian Cossacks origin and development should be studies in the context of its military, not economic, trade. Particularly, some Ukrainian historians by mistake consider that military structures of Cossacks, such as desiatok, sotnia, kurin, and Zaporozhian Sich as well, originated from structures of economic trade.