[EN] Olza (PL - Olza, CZ - Olše) is a river that divides and connects. It makes part of the border between Czechia and Poland. But historically, it has been the main communication artery of Cieszyn Silesia (PL - Śląsk Cieszyński; CZ - Těšínské Slezsko). People who live on both sides of the border, speak dialects of Czech (left bank) and Polish (rig