With OneSaas, you're able to integrate a month, 3 months, or even a year of historical sales data upon signing up. Different options are available on different plans, feel free to read more on this here
While it may be possible for us to sync more then a year, it's not something we are able to do as part of a standard integration as we find if we go back to far, issues can arise. Here are some of those common issues explained further:
Sometimes other systems we integrate with have API limitations of their own, for example, SalesForce. We use the SalesForce REST API to integrate, however this API also has set limits that can prevent us from sending too much data at once. This is usually okay, as majority of the time we'll only be sending little bits of data hourly, or daily - however, if we're going to push a whole years worth of data, we'll most likely hit these limits. As a result, we'll have to wait until the limits reset, then send the next portion of data. This isn't a very smooth process, however it's an outside limitation that's not in our control.
General Errors with Historical Data
One of the most common issues we find with historical data, is the fact that the older it is, the more outdated and inaccurate it tends to be. For example, more then a year ago you may have sold an item that you no longer sell today. Earlier this year, this item was deleted from your eCommerce system. The issue here, is that we still need to integrate sales data associated with the item, however as this item no longer exists, we're unable to integrate the data. The same situation can play out for older customers as well.