Importing old data into Metorik
Metorik tries to create a clone of your store's data. So all data - orders, customers, products, etc. (even if it's 10 years old and you have 100,000's of orders) - will be synced with Metorik.
But you may be wondering: What about my older data from outside of my stores? Perhaps you used a difference eCommerce system in the past or have data from other sources like a POS system.
To have that data in Metorik, all you need to is your old data into your current store. From there, Metorik will sync it and you'll have reports, etc. for the data right inside of Metorik.
There are a lot of advantages to this approach. Mainly, you get to keep and own a copy of all the data in your store.
For importing data into Shopify, take a look at their great help doc in on it.