The ICOW Colonial History Data Set

The ICOW colonial history data set attempts to identify colonial or other dependency relationships for each state over the past two centuries. This includes states that have ruled each state as a colony, dependency, League of Nations mandate, UN trust territory, or other type of possession, as well as states that have seceded from existing states and states that have merged into existing states. This should be most useful for analyses of a variety of possible propositions on the general impact of colonial rule on subsequent relations between the former colonizer and the former dependency, the impact of different countries' colonial policies on post-independence events (involving the former dependency and either internal problems or external relations with the former colonizer or with other states), and similar topics. It may also be useful in identifying cases for certain types of analysis (or perhaps "relevant dyads"), if former colonial powers are thought to have an interest in their former dependencies and their surroundings.

Project Participants

Current Status

This data set currently includes the basic colonial history of each state that was a member of the COW interstate system between 1816-2018. It will ultimately be updated with more information, likely including the years during which each colonial power ruled over the entity, multiple colonial powers for each entity where relevant (as many colonies changed hands over the years), and more information about the names of the specific colonial entities that made up each state's colonial history.

Download the Data and Documentation

All ICOW data sets may be downloaded freely, but we request several professional courtesies from users:


The following file includes the data and basic documentation:

Please note that this, like all ICOW data sets, uses the list of country codes in the COW interstate system. Please see that list for help in identifying which countries were involved in the events included in this data set, or for any questions about when each country was considered a sovereign, recognized state.


There is no current documentation available for this data set, beyond the codebook that is distributed in the download with the basic data. We have been working on documentation of the coding for each state in the data set, though, and will make this available once it is ready (which will depend on the pace of revisions - the file is approximately 300 pages long and still needs plenty of work to make it presentable and useful to users).

Data Set References

This data set has been used in a number of publications and working papers by various scholars, but it has not yet been described in detail in any published research (although that is expected to change in the relatively near future due to several projects I am currently working on with it). For now, it should be cited as an electronic resource:

Contact Information

The ICOW Colonial History data set is collected and maintained by Paul Hensel at the University of North Texas. Please contact him with any questions about the data set:
Last updated: 13 November 2018
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