The Chinese zodiac signs that clash are the Dragon and the Snake, as well as the Rooster and the Dog. These signs are considered incompatible due to their conflicting elements and characteristics. According to Chinese astrology, the Dragon and Snake are both of the Earth element, leading to a lack of harmony. Similarly, the Rooster and Dog are both of the Metal element, which also creates disharmony.

The Chinese zodiac is based on a 12-year cycle, with each year associated with an animal sign. The compatibility between signs is determined by their elements and the interactions between them. For example, the Dragon and Snake are both of the Earth element, which is associated with stability and practicality. However, when two Earth signs come together, it can lead to a lack of flexibility and communication issues, as both signs tend to be stubborn and inflexible.

Data from various Chinese astrology sources, such as the Chinese Zodiac Association, indicate that the Dragon and Snake, as well as the Rooster and Dog, are the least compatible signs in the Chinese zodiac. This is due to their conflicting elements and the challenges they face in harmonizing their personalities and values. For instance, the Dragon is known for its pride and independence, while the Snake is often seen as cunning and secretive. These traits can create tension and misunderstandings between the two signs.

Similarly, the Rooster and Dog are both of the Metal element, which is associated with strength and determination. However, their strong personalities and competitive nature can lead to conflicts and disagreements. The Rooster is known for its punctuality and organization, while the Dog is often seen as loyal and protective. When these traits clash, it can result in power struggles and communication breakdowns.

In conclusion, the Chinese zodiac signs that clash are the Dragon and the Snake, as well as the Rooster and the Dog. This incompatibility is due to their conflicting elements and personalities, which can lead to challenges in communication and harmony. According to Chinese astrology, these signs are less compatible and may require more effort to build a successful relationship.