There are written documentation of Egyptians using essential oils as early as 3500 BC. They used spikenard, citrus, oregano, myrrh, cedar, frankincense etc. for their therapeutic benefits.
Many archeological evidence have been found for the use of Incense and Aroma therapeutic principles during the method & ritual of preservation of bodies as well as the environment in the pyramids.
During religious rituals and other ceremonies the scent rising upwards is supposed to take our prayers, requests and gratitude towards heaven.
We find a very important and surprisingly similar correlation to lightening incense and religious ceremonies all across the world across various religions and faiths.