Business gift?

I recently received a small gift from a CEO of a company that my company was/is working with. He sent it to my home address. It wasn't much, but I found it strange. When he email me about it, he also asked me to try to get my boss to contact him because he hasn't been able to reach him. Should I assume that the gift was just to get me more motivated to get my boss to contact him, or should I send him a gift too?

If you live outside Japan, why not just follow the custom of the place you live.

Otherwise, I'm not sure what this gift was all about, but in Japan there is a custom of sending gifts one in July or early Auguest (o-chugen) and one in December (o-seibo) to all business partners, so maybe this was meant to be something like that.

It is always safe to send a gift in return. However, if the original sender is someone not so important to you or someone whom you think you'd never owe anything to, it's quite common to just say thank you and ignore it.