Forstinning's constituent communities include Aich, Aitersteinering, Berg, Köckmühle, Kressiermühle, Moos, Neupullach, Niederried, Salzburg, Schußmühle, Schwaberwegen, Sempt, Siegstätt, Steffelmühle, Wagmühle, Wind and Wolfmühle.

Forstinning's history begins in Sempt, where the area's transport hub lay, with the Grafenburg (“Count’s Castle”) as the trading post, with a market lent by the king (fiscale forum, 11th century), and the Reichshof (“Imperial Court”, curtis fiscalis, 934).

The first greatness that this far-flung spot knew, however, does not date merely from Bavarii times, but from much longer ago, as witnessed by many archaeological finds nearby.

The bronze ram figurine kept in the state's prehistoric collection may relate to the Celtic square dig site near Aitersteinering whose walls have been largely flattened by earthworks over time.

The find of a Bavarii row grave yard strengthens what the form of the placename already suggests: Forstinning was founded in the time when the land was first occupied by its current inhabitants.

Forstinning has canting arms in which one of the charges – the two stylized fir trees – suggests the key word element in the community's name, Forst – German for “forest”.

The arms might heraldically be described thus: In azure a three-knolled hill (Dreiberg in German heraldry) Or, on each flanking knoll a fir tree Or, between which a cross argent.

According to official statistics, 10 people on the social insurance contribution rolls were employed in agriculture and forestry in 1998 in Forstinning.

Public transport in Forstinning consists of buslines to Munich East Station (München-Ostbahnhof), Markt Schwaben, Gars, Hohenlinden and Ebersberg.

In 1999 the following institutions could be found in Forstinning: Further schooling is available in Markt Schwaben (Gymnasium, Realschule, Hauptschule) as well as Erding (Berufsschule, Berufsoberschule, Fachoberschule).