Archaeological research demonstrates that Georgia has been involved in commerce with many lands and empires since ancient times, largely due its location on the Black Sea and later on the historical Silk Road. Gold, silver, copper and iron have been mined in the Caucasus Mountains. Georgian wine making is a very old tradition and a key branch of the country's economy. The country has sizeable hydropower resources. Throughout Georgia's modern history agriculture and tourism have been principal economic sectors, because of the country's climate and topography.