The early Romanov Tsars were not too successful trying to marry off their sons and daughters to the princes and princesses of the foreign royal houses. The Romanov Grand Duchesses were doomed to spend their lives in Terem (ladies' quarters in the Moscow Kremlin) in solitude, as they were almost totally isolated from the outside world by the strict court rules.

It wasn't until in the fourth generation that things changed, as Tsarevich Alexei Petrovich married Princess Charlotte of Braunschweig-Wolfenb�ttel in 1711. In the same time the sons of Petr I The Great's half-brother Ivan V were married to German princesses, too.

Hereafter, the spouses of the Romanov Emperors were almost invariably German princesses, with some exceptions, like Alexandr III, who married Maria Fedorovna, a Danish Princess.

As the Grand Dukes and Grand Duchesses married foreign princesses, the Romanov blood mixed with Central European royal blood. Later on, their children and grandchildren were married all across Europe. As a result, most eminent members of the current European Royal Houses can count Russian Emperors among their ancestors.  

These charts illustrate some of the connections between the Romanov Family and other European Royal Houses.

Crest Nikolai I -- Charles, Prince of Wales (6 Generations)
Crest Pavel I -- Beatrix, Queen of the Netherlands (6 Generations)
Crest Nikolai I -- Konstantinos II, King of the Hellenes (6 Generations)
Crest Nikolai I -- Margrethe II, Queen of Denmark (6 Generations)
Crest Nikolai I -- Felipe Juan Pablo of Spain, Prince of Asturias (7 Generations)
Crest Pavel I -- Carl XVI Gustaf, King of Sweden (8 Generations)
Crest Pavel I -- Wilhelm II, German Emperor (5 Generations)
Crest Nikolai I -- Georg Friedrich, Prince of Prussia, Head of the Prussian Royal Family (7 Generations)