I am not Asian but live in area of London with a high South Asian population and every one of my Asian descent work colleagues seems to have someone with IBD in the family! I was told by a GI that the prevalence of IBD in 2nd generation and later Asians in the UK is now as high as it is in the Ashkenazy Jewish population which used to be always highlighted in the UK as the population at biggest risk of IBD.
Someone once linked on here a paper specificially about
growth of IBD in Asian descent children, if you do some searching you may find it.
This is an interesting paper on IBD and global spread www.worldgastroenterology.org/assets/downloads/en/pdf/guidelines/21_inflammatory_bowel_disease.pdf