Long before the invention of the combustion engine, industrial revolution and climate change, the crude oil of Naftalan, a little town in the plains of Azerbaijan, was used as a remedy for numerous skin diseases and rheumatism. The heavy oil is rich in naphthalene, a hydrocarbon that is the active ingredient in coal tar soaps, normally used to treat psoriasis. Even Marco Polo noted that this special oil was commonly traded on the routes toward China.
During Soviet times, Naftalan, was home to different Sanatoria and still now people come from most ex-Soviet countries to take an oil bath. The procedure is simple, the oil is warmed at 40°C and the patient lies in it for 10 minutes, not more since naphthalene evaporates easily and it is carcinogenic if inhaled. After a daily bath the customers can relax and profit of other treatments during the rest of the day.