You cannot do anything to prevent a rival from poaching your people. But you can do some things that help your people stay when they are being poached.
Here's 3 simple ideas:
1) Show Them Their Value: Help them see value in what they are doing in your company. Show them how their contributions are affecting and impacting your team and company.
2) Praise Them: In Asian companies, this action probably scores really low and yet, people loved to be acknowledged for the good work they do. Be intentional and deliberate when you praise your people. Don't be patronising or superficial. But attach your praise to a specific behaviour.
3) Create An Environment That Blossoms People: You can't really change the way people think, feel or behave. But you certainly can change the environment that can blossom them. What can you do specifically for a specific individual that would specifically help him/her do better?