Explanation
A network interface can exist in the same, or different resource group, than the virtual machine you attach it to, or the virtual network you connect it to.
The virtual machine you attach a network interface to and the virtual network you connect it to must exist in the same location, also referred to as a region.
Note, Resource groups can span multiple Regions, but VNets only can hold resources (VMs, Network Adapters) that exists in the same region.
So in this scenario, you need to create VNET1 in any RG and set location as East Asia.
Reference:
https://docs.microsoft.com/en-us/azure/virtual-network/virtual-network-network-interface