The present invention relates to substituted heterocyclic compounds of Formula I or XI: or pharmaceutically acceptable salts or N-oxides or quaternary ammonium salts thereof wherein constituent members are provided hereinwith, as well as their compositions and methods of use, which are histamine H4 receptor inhibitors useful in the treatment of histamine H4 receptor-associated conditions or diseases or disorders including, for example, inflammatory diseases or disorders, pruritus, and pain.