Chinese Peasant Knives. Age?

[Drabant1701]

I was bidding on a nice Indo-Persian dagger in an auction, I also casually bid on some stuff that I thought looked interesting. I won these three knifes that I have concluded is Asian farmers knifes, maybe for cutting opium flowers. So... does anyone recognice the mark on the blade od the smallest one? I think the antlope horn one and the small one is first half of the 20th century, but the one with ivory?, walrus? grip looks pretty old, do you think its an 19th century knife. This is not my area at all so I do not know how long these type of knife has been around. Anyways, if you have any knowledge on the subject you want to add, please do so.