With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The Mongol invasions caused the fall of the Kingdom of Georgia.
text_B: Lutz E. von Padberg -LRB- born 22 February 1950 -RRB- is a German historian whose specialty is medieval history and in particular the Christianization of the Germanic peoples .. the Christianization of the Germanic peoples. Germanic Christianity. He is an expert on Saint Boniface , having written biographies of the saint and studies of his veneration .. Saint Boniface. Saint Boniface
not_related.