Moving a wiki to Miraheze

Moving wiki hosted by yourself, Wikia, or any other MediaWiki host is possible. You just need 'XML' file with the history of your wiki.

Exporting from Wikia
Wikia provides XML dump of wikis in. It may be outdated - have your wiki administrators click "Send request" button there. If your wiki has no active administrators, you'll have to contact Wikia support to click it for you. See Wikia's own documentation for this. Download "Current pages and history" regardless of the size, this is because of Creative Commons' attribution requirements.

Exporting from Special:Export
You can export your wiki using Special:Export. That page is self-explanatory, just make sure to uncheck "" because of the legal concerns outlined above. If this fails, you'll have to use the method below.

Exporting via maintenance scripts
If you have access to the server where MediaWiki is installed, issue dumpBackup.php in the wiki.

Caveats
This method does not export image files. You will have to copy the file and give it to System administrators for processing.

Do it yourself
If your dump is really small (less than few KBs), you can try Special:Import on your wiki. (Don't try this command in Meta!)

Request import
If your file is big enough that MediaWiki fails to process in due time, it has to be processed by Miraheze system administrators. Please request import using this form (Phabricator account required), and send your actual XML dump to staff@undefinedmiraheze.org. Image import should also follow this way, too.