How were the Hancock sisters slaves?

[Warmmedown]

Was Amazon Lily raided? Or were they kidnapped elsewhere? Amazon Lily had Shaky and Gloriosa and the whole island is pretty strong.

 

[SSJ2]

I'd assume Shakky was already living at Sabaody, and Gloriosa is an old lady now. Amazon Lily is in the Calm Belt so I can't see it being raided by anybody ordinary. They were probably captured at sea.