Four years after the September 11 attacks, we’re just beginning to learn about the appalling reaction to these atrocities in Muslim communities in Europe: In Germany, Muslims grow apart. (Hat tip: Still Rolling.)

There is a new wall rising in Berlin. Looking over that wall, one sees the parallel world of the Islamic suburbs. It’s a world in which women, unlike some Muslim women in Europe who have risen to expansive lives, are still subject to arranged marriages and the control of their families.

To cross this wall you have to go to the city’s central and northern districts, to Kreuzberg, Neukölln and Wedding, and you will find yourself in a world unknown to most Berliners. Until recently, most held to the illusion that living together with some 300,000 Muslim immigrants and children of immigrants was basically working.

Take Neukölln. The district is proud of the fact that it houses citizens of 165 nations. Some 40 percent of these, by far the largest group, are Turks and Kurds; the second-largest group consists of Arabs.

Racially motivated attacks occur regularly in Brandenburg, the former East German state that surrounds Berlin, where foreigners are few, accounting for only about 2 percent of the population. But such attacks hardly ever happen in Neukölln. Stefanie Vogelsang, a councilwoman from Neukölln, says that residents talk about “our Turks” in an unmistakably friendly way, although they are less friendly when it comes to Arabs, who arrived after the Turks, often illegally.

But tolerance of Muslim immigrants began to change in the aftermath of Sept. 11, 2001. Parallel to the declarations of “unconditional solidarity” with Americans by the German majority, rallies of another sort were taking place in Neukölln and Kreuzberg.

Bottle rockets were set off from building courtyards, a poor man’s fireworks: two rockets here, three rockets there. Altogether, hundreds of rockets were shooting skyward in celebration, just as most Berliners were searching for words to express their horror.

For many German residents in Neukölln and Kreuzberg, Vogelsang recalls, that was the first time they stopped to wonder who their neighbors really were.

And US mainstream media could not have cared less.