A mixture of crushed rock and tar with was a pre curser to modern Asphalt.
Of course you only hear the word now days by nit wit news people who picked up the term after the 1972 TWA hi-jacking where British reporters on the scene referred to the airliner "sitting on the tarmac". In British terms they commonly use tarmac like we in the USA would use the word "Asphalt". As is so common with reporters they like to repeat words and phrases that have an International flavor whether they know the meaning or not.
You are driving down an old country road constructed with the old fashioned process of rock and tar called "tarmac"