I'm trying to find a dataset that contains number of historical natural disasters by country in the longest lapse of time possible. Would appreciate your help.
In the academic literature EM-DAT seems to be the standard. It is quite a comprehensive dataset covering ~21,000 disasters worldwide and going back to 1900 (don't know if that is historical enough). It also classifies disasters according to group and subgroup which can be useful.
Includes data and analysis
NCEI archives and assimilates tsunami, earthquake and volcano data to support research, planning, response and mitigation. Long-term data, including photographs, can be used to establish the history of natural hazard occurrences and help mitigate against future events.