Othello is full of geographical symbolism. The play takes place in two locations, Venice and Cyprus, while it mentions war with a third, the Turks (Asia-Minor mainland). As there are also three main characters, Venice is represented by Iago; Cyprus is represented by Desdemona; and the Turks are represented by Othello.
Venice was, at the time, one of the most powerful and cosmopolitan city-states in Europe. As such, it is symbolic of the white, Christian, European values. It is run by the Senate and the Duke, symbols of law and order. Their assembly in Act I involves two important points of business: to send Othello as commanding officer to Cyprus and to condone his elopement with Desdemona. In short, Venice's poster-children are Iago and Cassio, strong, white, Christian military males.
Cyprus, on the other hand, is more volatile and wild. It is an island, so it is isolated from colonial law and government. More, it is a military strategic target for both the Venitians and the Turks. So, it is much like Desdemona, for she is a target of battle between Iago and Othello. She too is isolated from a community of women. Cypurs is the location where Iago's master plan gains hold, where Othello goes mad with jealousy, and where the murders and suicide takes place. It is a place of chaos and death.
Although it does not appear in the play, the Turks' threat is symbolic of the Muslim (Moorish) threats to the Christian world. They represent the Moor's invasion of Christendom. The Turks' navies are destroyed in the storm in Act II, but the Turk continues the play thereafter. Their threat lives on in Othello, who is an obvious racial and sexual threat to Iago's white Christian values.