Original: Returning to the continent he followed the invitation of Tsar Alexander I to come to St. Petersburg, where he lived so briefly he never prepared a meal for the Tsar before returning to Paris, where he was chef to banker James Mayer Rothschild.
Simplified: He returned to Europe to work for Tsar Alexander I in St. Petersburg, before returning to Paris, where he was chef to banker James Mayer Rothschild.