Regional alliance

Would regional alliance consists of companies of one region, for example east europe, be successful. What if to create one?

There is very little point IMHO. The whole point of interlining and alliances is to gain more passengers by working as a collective. If you have airlines all the same region they are likely to be taking from the same pool of passengers. If you have worldwide you are more likely to be taking from a different (non-competing) pool. A lot of new players waste their time creating regional alliances, which are in effect alliances with your competitors.

If we use Germany as an example. Airline a is FRA based, and airline b is MUC based. They do not compete on any routes directly but how’s about pax wanting to go LHR-IST. They will now be split between airline a via Fra And airline b via muc…

I mean not one country, but different in one region. Of cause, such a method would not be useful in Europe because of EU treaty, and all of the countries which are in EU are competitors. But what if tha's some other countries with low passenger flow and high number of competitors?

for example some alliance which unite a second-stage players in domestic markets with law international route network in Asia,or fomer USSR or in Americas. I think such union may strenghten their positions and they will play more successful against the leaders in their markets. Am i mistaken?

The idea of creating such an alliance is quite interesting.... If the quantity of members from one country of the region would not be more then one. 

Is it legal to create a regional alliance, monopolize the area and then pushing out competitors altogether?

Why not? The alliance means that their participants - no less then two different enterprises... and this doesn't go against the rules, i think