Restore WhatsApp History from old Number I'm not sure if this is the right place to ask but maybe someone can help me out.

I lived in Australia for a few month and got a new number on my iPhone. I backed up my WhatsApp a few times while having that new number. When I got back to Germany I returned to my old number on the same phone. I did a factory reset after I came back and then switched to my german number with a clean WhatsApp history. 

Now here is my question: Can I still restore my old history (Australian number) onto my new WhatsApp? 

I'm not even sure if my Australian number still exists since I don't have the SIM anymore.
Afaik there is no other possibility restoring WhatsApp messages than doing it via an iPhone backup. WhatsApp officially does not store messages except those, which can't be directly delivered. WhatsApp will always refuse giving you access to this kind of data.

So your only chance will be to find an old backup of your device and try to back your device up with that old state.

Please also provide some information, if your issue is solved or what other step you took to figure it out.

Edit to be clear: WhatsApp history backups are only stored in your device's backup :)