I just discovered an etymology that surprised me: barrio, which the OED takes back only to “Sp. barrio district, suburb,” is now considered to be, as AHD puts it, “Spanish, from Arabic barrī, of an open area, from barr, open area. See brr in Appendix II.” And from Appendix II we learn that it’s related to birr, the unit of currency in Ethiopia. (According to Wikipedia, “Before 1976, dollar was the official English translation of birr. Today, it is officially birr in English as well.”)
This is quite surprising … I had thought it was related to borough.
The RAE suggests a further meaning of “wild” for the Arabic root, here: http://rae2.es/barrio . Steingass agrees with them: http://dsal.uchicago.edu/cgi-bin/philologic/getobject.pl?c.0:1:9012.steingass –I wonder why the AHD doesn’t mention this.
“Dollar” also used to be common for referring to Chinese currency in English.
I think the unit of currency in Ehiopia probably stems from a similar word bur which is a grain of some sort.
Bur also means a state of contentment.
The word bar which you refer to meaning open space actually stems from the ward for land. Wild animals live on the land which is where bari stems from.