Just a few months ago, I traveled on horseback through northwestern Mongolia, a remote region of herdsmen and nomads. Yet now that I am back in New York City--an urban environment that seems about as un-nomadic as you can get--my exotic journey through mountains and steppes suddenly feels especially relevant to my life, as well as to my mission as a rabbi.

Within the first several days of my journey--after traversing the habitat of ibex, wolves and endangered snow leopards--I came across a celebration. A young man was about to be married, and relatives and neighbors had gathered to build him a ger--a circular, transportable, tentlike structure--as a present.

When I arrived, the ger was half finished--its wooden frame stood bare, like a skeleton awaiting the flesh of felt that would soon envelop and protect this new home. The men used hammers, saws and sinews to build and affix the frame, while the women scraped the felt covering that would shelter the young couple from the weather.

I tried my best to do my part, which consisted of schmoozing, through a translator, with the groom's father and uncles, and taking photos of the children. Since I had to leave the event to move on with my own trip, the experience concluded with a midafternoon feast of candy and homemade cheese curds, followed by celebratory toasts of vodka and fermented mare's milk. Never before had I felt so welcomed, even as a total stranger, into somebody else's world--their party had become my party.

This powerful communitarian sensibility is related as much to necessity as it is to morality. No one in that world could have survived without the active help of others. What I saw was a form of humanitarian aid that wasn't institutional or solicited, but commonplace and expected.

One of the great nomads in the Biblical tradition is Abraham, "the son of a wandering Aramaean." There's a narrative in the book of Genesis that is often used as a model for how we should behave toward others. Three strangers unexpectedly appear in the desert and approach the tent of Abraham and Sarah. The patriarch rushes out to greet them and invites them into his home for food and shelter.

It's clear that Abraham and his wife had an "open tent" policy. What I saw in Mongolia afforded me an unforgettable glimpse into that world of Abraham and Sarah, the world of the nomad. While that society isn't a perfect one, it inculcates a culture of interdependence and washes away the illusion of self-reliance that so many of us Americans have bought into--more now, arguably, than ever before. It shows us the lunacy of trying to go it alone, and the truth that we don't have to.

Ours is a culture of excessive individualism, of the radical pursuit of our own needs and desires--and, on the global level, of unilateralism. So what is it that we need to atone for? Not for having packed up our tents and moved into town houses; not for having traded in our camels for cars. But for having, in the process, abandoned our commitment to community.

With the external structures of tribalism gone, how can we regain its core values? If we fail to face this existential struggle, then we will have taken the gift of Abraham and Sarah's open tent and sealed its entrance shut. In doing so, we will have sealed the entrance to our hearts.

The narcissistic impulses so prevalent today are this society's mask. Beneath that mask, we are needier than ever. We live in an era of disturbing violence, of terror alerts, of alienation from even our own families. We live during a dark period in time, and its evolution is uncertain and unsettling.

As a Jew, I come from a nation of nomads. Ours is a tribal religion with tribal roots. Most of the answers to society's problems--our fears, anxieties and feelings of loneliness--are not in self-help books or weekend getaways, but in our own spiritual heritage. Judaism, like other ancient religions, offers correctives, pathways that allow us to regain the anchors of community we so deeply crave.

There are many rites and rituals that can help us improve our moral characters and cultivate a more harmonious world. But first, we must accept one of the basic rules of tribal life--that the motivation for our behavior is grounded, not in what we want to do, but in what we ought to do.

Abraham's tent was exposed to every direction--it was welcoming, but it made him vulnerable. That is precisely the point--it is only through vulnerability that genuine community can emerge, that commitment and compassion become intertwined and inseparable. Both require a risk on our part, and both necessitate that we make a leap of faith. Yet that leap focuses only on the self; religion urges us to take the next step, to make a leap for humanity.

And we don't need to go to Mongolia to find our jumping-off point.