"Avraham gave all he had to Yitzchak. And to the children of the concubines of Avraham's, Avraham gave gifts, and he sent them away from Yitzchak his son, while he was still alive, eastward to the land of the east." Breishis, Parshas Chayei Sarah. (Gen. 25:5-6 in the Sapirstein Edition of Rashi: The Artscroll Series, pp. 266-7).
The question is asked, if Avraham just gave everything he owned to Yitzchak, then what did he give to his other children? Rashi addresses this by saying, "Our Rabbis explained, he gave over to them a name of an impurity. " (Id.) In other words, it was a spiritual gift. What was the nature of this spiritual gift?
The Gemara, in Sanhedrin 91a goes on to explain that it was "A name by whose pronunciation they would be able to perform sorcery. The 'gifts' here do not refer to property, for Avraham had already transferred ownership of all of his property to Yitzchak." (Id.)
To summarize: Avraham sent his children to the east with powerful spiritual gifts, and those children presumably became the progenitors of the spiritual traditions of the east that we have today.
I understand why American Jews are often dissatisfied with the experiences they've had in organized Jewish life growing up, and seek something more spiritually satisfying as adults. But I have wondered why these Jews are so attracted to Eastern religions specifically.
This source makes a good argument for why that is. Apparently, the root of those spiritual traditions is in Torah and in the acknowledgment of the One True G-d, however obscured those roots have become today. There is obviously still residual power from that original spiritual energy that Avraham sent, enough so to draw spiritual seekers to attempt to slake their thirst there.
Over the course of this week I'm going to see if I can find any further information on this subject.