Perhaps you should try some spelling variations:
"american colonization empire" » "americans colonization empire", "american colonization pre", "american colonization exile", "american consolidation empire"
"american colonial empire" » "american colonies empire", "american colonial empires"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"american colonial empire\") OR (\"american colonization empire\"))".
• Removing quotes may allow a broader search: (( american colonial empire ) OR ( american colonization empire )).
• Adding a wildcard symbol may retrieve word variants: (("american colonial empire") OR ("american colonization empire"))*.