The "Barbacoa" version is one possible version of where the term "Barbecue" or "BBQ" comes. There are other versions that claim to be just as valid.
Another version claims it came from roadsides "Bars" in the south offering inexpensive smoked meats to get you to come in and buy "Beer" & a game of "Cue Ball" (pool). Bar, Beer & Cue eventually got shortened to "Barbecue" or "BBQ". This version could very well explain why so many think of BBQ as a "Southern" thing.
Who knows for sure?
And YES, we "Northern" boys & girls are familiar with BBQ. It may conjure up different thoughts to us than in Greensboro, NC, which will think of it differently than Memphis, TN, or Lockhart, TX, or Jamaica (where jerk reigns), etc. Hawaii has their Kalua Pig which is traditionally cooked in the ground. It's different everywhere you go, and each region seems to take a lot of pride in their version of it.
Here in Ohio, growing up we had what we'd call a "BBQ" or "Cookout" where anything cooked over a fire was fare game (Pork, Steaks, Chicken, Burgers, Sausages, Ribs (Beef & Pork), you name it). About once a year we'd go to what we called a "Pig Roast" (similar to a Carolina Pig Pickin').
All I know is I love to "Barbecue" and eat Barbecue in it's many forms (one look at me you might be able to tell)!
Any other good stories of where the term "BBQ" originated?