If you are implementing Odoo from scratch and want to move five years of data from your old system, the recommended approach is to first identify which data is truly needed in the new system. Typically, companies import master data such as customers, vendors, products, employees, and opening balances, along with any essential historical records.

Odoo provides import tools that allow you to upload data using Excel (.xlsx) or CSV files. You can prepare separate spreadsheets for each type of data and import them into the corresponding modules.

For a small or medium amount of data, this process can usually be handled internally. However, if you have a large volume of historical data, complex business processes, or customizations in your old system, it is advisable to work with Odoo or an experienced Odoo partner. They can help plan the migration, ensure data accuracy, and reduce the risk of issues during the transition.

You first need to distinguish how many modules your original system has, such as customer management, human resources, sales, and payment/collection, or even more functional modules. You must separate them clearly. At the same time, you need to understand how your old system started from 0 to 10, with a complete process. Then gradually import the data step by step.