The search function in the iPhones / iPads standard calendar app only searches for calendar entries up to a maximum of 1 year back.
CalSearch fixes this and searches the various calendars of the iPhone for any search term, even more than 1 year back. The search period and the calendars to be searched are configurable.
CalSearch is a free app with no ads or in-app purchases - we dont make any money with it. Please understand that we cannot offer any support as a result.