Complex sentence: More than 350,000 Feyli Kurds had been deported to Iran as a result of the persecution campaigns and at least 15,000 Feyli Kurds are lost, their remainings haven't been found yet.
Split into simpler sentences: More than 350,000 Feyli Kurds had been deported to Iran as a result of the persecution campaigns. At least 15,000 Feyli Kurds are lost, their remainings haven't been found yet.