Given the task definition and input, reply with output. In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.

Passage: Papal calls for renewed holy war at the end of the twelfth century inspired not only the disastrous Fourth Crusade that sacked Constantinople in 1204, but also a series of simultaneous "Northern Crusades" that are less fully covered in English-language popular history, but which were more successful in the long run. Before the crusades, the region of Livonia was a mixed outpost, a pagan society where merchants from the Hanseatic League encountered merchants of Novgorod, and where Germanic, Scandinavian, and Russian trade, culture, and cults all mingled. The specific ethnic groups that intermingled and traded with the Germans, Danish, Swedish, and Russians here included the Wends, who were merchants from Lubeck, the Estonians, the Karelians, the Kuronians, the Lettgallians, the Semgallians (sometimes known as the Letts), the Livonians and the Lithuanians. The Western merchants would trade silver, textiles, and other luxury goods for furs, beeswax, honey, leather, dried fish, and amber. Livonia had been an especially promising location in terms of resources, and Arnold of Lubeck, in his Chronicle of the Slavs wrote that the land was "abundant in many riches" and was "fertile in fields, plentiful in pastures, irrigated by rivers", and "also sufficiently rich in fish and forested with trees".
Link Information: none Answer: none
What were the main groups involved in the event that resulted in the sacking of Constantinople in 1204?