sets like this are being made for the French market in India now, and some caution needs to be used when purcasing 'old' sets in this style. India, (21st century) but in a 20 th century style
Post 1948, probably Nothern Africa. withdrawn from sale as ivory of this date has now been outlawed.
20c horn also French colonies.
Mike Darlows book Turned Chessmen, showing the shape of a 20th century regence set, note the pawn shape which is diagnostic.
and a 20th century set
20th century
early 20th century, possibly late 19th century.
19th century, (note the change in the shape of the pawn)
19th century without knights head.
late 19th century
19th century
early 19th century
18th century or earlier