Among Indonesian coffees, the most famous is Mandheling, widely popular for its rich, full-bodied flavor. At FrontStreet Coffee, the entry-level selection Lintong Mandheling and the well-known PWN Golden Mandheling are both bestsellers.

Mandheling is also called "Sumatra coffee." Sumatra is the largest island in Indonesia, and the island is mainly divided into two parts: the Barisan Mountains in the west and the lowland plains in the east. Arabica varieties are mainly concentrated in the Barisan Mountains in the northwest of the island, in the Gayo production area of the Aceh Special Region and the Lintong production area of North Sumatra Province. The Barisan Mountains provide multiple volcanic mountain ranges and lakes here, making it very suitable for growing Arabica varieties, while the lowland areas in the southeast of the island mainly grow Robusta varieties.

The Lintong production area is located south of Medan, the provincial capital of Sumatra. Here is Lake Toba, the largest volcanic lake in the world, with many high mountains around its shores. The soil in this area is rich in minerals due to past volcanic eruptions, and coffee is mainly grown on the slopes at 1400-1800 m by the lake. FrontStreet's entry-level selection Lintong Mandheling comes from here; after brewing, it has herbal and dark chocolate flavors, a caramel-like full body, and a high sweet aftertaste.

The name of the Gayo production area comes from the Gayo people. This production area is located in the mountainous area of Aceh Province at an altitude of 1300-1600 m. There are also many volcanoes and numerous volcanic lakes here, among which the most famous coffee-growing area is located at Lake Laut Tawar. FrontStreet's PWM Golden Mandheling comes from the Gayo production area. After brewing, it enters with flavors of toasted bread, pine, caramel, and cocoa; the body is fragrant, rich, and full, with varied overall layers, intense and balanced, and a lasting caramel sweetness in the finish.

Both Mandheling coffees come from the Sumatra production area in Indonesia, and both use the Ateng variety. Many people may think this is a new coffee variety, but it is not; in fact, Ateng is the Catimor variety.

Only Catimor grown in Sumatra and on Indonesia's native islands can be called Ateng. Catimor is a hybrid between Timor and Caturra, producing the first generation F1 hybrid variety group. The code for Catimor is T-8667, but it still needs to be defined through selection and breeding, so Catimor is not a single variety but a variety group with similar lineage.

Among them, the Timor variety is locally called "Tim Tim." This is a natural hybrid of Arabica and Robusta varieties discovered on the island of East Timor. It is classified within the scope of Arabica plants, but to be precise, it carries disease-resistance genes from Robusta, and precisely because of this, Catimor, obtained by crossing Timor and Caturra, also has resistance to coffee leaf rust.

In addition, Caturra is a natural mutation of Bourbon, and because it has a single-gene mutation, it causes the plant to grow smaller. Catimor likewise inherits this characteristic from Caturra: the plant as a whole is short, so it can be planted more densely, and therefore yields are relatively high, and it can be planted at lower-altitude areas, making it very well suited to Indonesia's local island climate. However, Catimor is relatively susceptible to attack and impact from the fungal disease Ojo de Gallo, coffee berry borer, and nematodes.

As a common coffee variety on the island of Sumatra, the name Ateng mainly comes from the fact that it was first discovered in Aceh Tengah in the central part of the Aceh region, and it was named after the place. Ateng is a hybrid descendant of Caturra and Tim, varieties of Arabica Bourbon, and has several subtypes, carrying 1/4 Robusta lineage, possessing extremely high disease resistance, and is widely planted in Sumatra and other small Indonesian islands. Qianjie's Golden Mandheling coffee is the Ateng variety.