CryptoKylin is the name of one of the two main EOS testnets currently running. It’s chain ID is: 5fff1dae8dc8e2fc4d5b23b2c7665c97f9e9d8edf2b6485a86ba311c25639191. More information about it can be found at the CryptoKylin home page or at a Kylin Block Explorer.