The history of the word "country" is a research project, first published as A New English Dictionary on Historical Principles; Founded Mainly on the Materials Collected by The Philological Society, not just known as the Oxford English Dictionary. Originally, the word, from Middle French (meaning region, area of land delimited by natural or political boundaries) was used in a broader sense, as they say (sense 1) "The land of a person's birth, citizenship, residence, etc.; one's homeland", or (sense 2) "Land, terrain, or a region of undefined extent, esp. considered with regard to its physical characteristics" such as chalk country, fen country, stag-hunting country, country of the red deer. The latter use is fairly common in American English. I do not think the meaning has changed much over time, instead, politics has changed.