What is the importance of Verbov Island in the novel, The Yiddish Policemen’s Union?

Verbov Island is inhabited entirely by highly orthodox Jews called Verbovers. Verbov Island is the residence of crime boss Heskel Shpilman. When Landsman and Berko go to Verbov Island to interrogate Heskel Shpilman, they notice that no one in the neighborhood seems to have made any preparations for post-Reversion relocation. Landsman eventually discovers that Heskel Shpilman has arranged for all residents of Verbov Island to be awarded permanent resident status in exchange for his help organizing a large-scale religious ritual involving Jerusalem.