Write SQL query to solve given problem: Among the sales people, who are hired prior to 2010?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(T1.BusinessEntityID) FROM Employee AS T1 INNER JOIN Person AS T2 ON T1.BusinessEntityID = T2.BusinessEntityID WHERE T2.PersonType = 'SP' AND SUBSTR(T1.HireDate, 0, 4) < 2010