Beautifully designed Asian plate

This is a plate (diameter 40 cm / 15.8 in) I found in Kuching, Sarawak, Malaysia from a shop owned by a Chinese Malay lady. I bought it simply because the design really caught my eye, it seems unusual to me, especially amongst the other more traditional looking Chinese plates that were there. The shop owner couldn't really tell me anything about it except that it was from her late father's collection and that the price on the back (which she honoured) was the price for which her father put it up for sale 20 years ago. She was unsure how much older than that it was though. It would be nice to know some more information about it so if anybody has any idea or can share some wisdom about the type of design, country/region of origin, age, signature or what the signs mean (and if I've pictured them right way up!) that would be wonderful to find out! Thanks!