The prosperity of the country was due in a considerable measure to the extension of agriculture by reclaiming virgin lands and making new settlements on them. Before the coming of the Muslims vast tracts of alluvial lands, especially in the southern regions, were still covered forests. The attention of the new comers was directed to the reclamation of these lands partly for the purpose of settling immigrants who poured into the country from time to time, and partly for increasing its agricultural out – put by bringing more of those fertile tracts under cultivation.  The work seems to have been undertaken quite early in the period, though the exact time and the areas involved are not known, for its salutary effects were observed in the first half of the fourteenth century. A Chinese account of 1349-50 states: “These people owe all their tranquillity and prosperity to themselves, for its source lies in their devotion to agriculture whereby a land originally covered with jungle has been reclaimed by their unremitting toil in tilling and planting. [Source: History of The Muslims of Bengal Vol 1B pages  931-932 Publisher: Imam Muhammad Bin Sa’ud University. First Edition 1406H/1985]

Although in general the Muslims of Bengal followed the injunctions of Islaam, certain innovations and Un-Islamic practices were prevalent among them, particularly later in the period. The existence of such innovations and superstitions have too often been explained as a result of Bengal Muslims’ being mostly converts from Hindus etc who are said to have retained many of their previous Un-Islamic beliefs and practices.  Such a view is clearly superficial. A little closer look would at once show that the innovations and superstitions that are noticeable among the Muslims of Bengal were in large measure imported by the immigrant Muslims themselves, though these received further accretions from local Un-Islamic beliefs and practices. Of the innovations that definitely came along with the immigrant Muslims and that which was the most far-reaching in its effects and influence was Sufism. There is a considerable literature on the subject in various languages, and it not necessary here to enter into the academic debate as to whether Sufism grew out of European or Indian influences. Suffice to note here that Islam does not countenance asceticism and mysticism. Yet from the second century of its history these two trends made their inroads into the ranks of the Muslims and in course of time there came into being a class of mystics known as Sufis. [Source: History of The Muslims of Bengal Vol 1B page 799-800. Publisher: Imam Muhammad Bin Sa’ud University. First Edition 1406H/1985]

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Regarding Sufi Practices, the Article on this link http://www.salaficentre.com/2015/12/a-brief-acquaintance-with-the-rise-origins-and-spread-of-grave-worship-in-the-ummah-by-shaikh-shamsuddeen-al-afghaani-as-salafi-rahimahullaah/   gives a brief acquaintance with the origin of Sufi practices, such as grave worship etc